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Save AP Stat 1997 For Later EASED EXAM
ee ea ee
AP Statistics
CONTAINS:
© Multiple-Choice Questions and Answer Key
© Free-Response Questions, Scoring Guidelines,
and Sample Student Responses and Commentary
© Statistical Information About Student
Performance on the 1997 Exam
Advanced Placement Program”College Board Regional Offic
National Office: Wade Cusry/Philip Arbotino/Charlone Gill/Erederick Wright
5 Columbus Avenue, New York, NY 10023-6992
(212) 713-8000
E-mail: weury
 
  
al
  
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New York, Pennsylvania, and Puerto Rico)
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E-mail: forown @e
 
 
Negeboard org, skampmeies@eall
 
hoard.or, millet @collegeboard.or
 
mraibon@collegeboard.org
(Serving Arkansas, New Mexico, Oklahoma, and Texas)
Dallas/Fi. Worth Memoplex AP Office: Kay Wil
P.O, Box 19666, Room 108, 600 South West Street, Arlington, TX 76019
@171272-7200
E-mail: kwilson@collegeboaré.or3
 
  
 
   
Wester: Claire Pelton, Gail Chapman
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E-mail: cpelton@collegeboard.org,
 
hapman@collegeboard.ong
 
(Serving Alaska, Asienna, California, Colorado, Hawaii, Idaho, Montana, Nevada, Oregon, Utah, Washington, and Wyoming)
AP Consultant in Canada: George Ewontis
212-1755 Springfield Road
Kelowna, B.C., Canada VIY SVS
{250} 861-9050; (800) 667-4548 in Canada only
E-mail: gewonus@ap.ca- The Advanced Placement Examination _
in Statistics
Contains:
@ Maltiple-Choice Questions and Answer Key
® Free-Response Questions, Scoring Guidelines, and Sample
Student Responses and Commentary
® Statistical Information about Student Performance
on the 1997 Exam‘This booklet was palace y Elbetonl Testing Service (ETS), which deol and amines
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‘THE COLLEGE BOARD: EDUCATIONAL EXCELLENCE FOR ALL, STUDENTS,Ci The AP Process
 
| Who Develops the AP Statistics Exam?
© How Do They Develop It?
® Section I
# Section II
= Question Types
1 Multiple Choice
1 Free Response
Scoring che Exam
Who Scores the AP Statistics Exam?
= Ensuring Accuracy
1 How the Scoring Guidelines are Created
w Training Faculty Consultants to Apply the
Scoring Guidelines
= Maintaining the Scoring Guidelines
Preparing Students for the Exam
| Teacher Support
‘This chapter will give you a brief overview of what
goes on behind the scenes during the development and,
grading of the AP Sratisties Exam. You can find more
derailed information in the “Technical Corner” of the
AD website (wwvzcollegeboard.org/ap)
Who Develops the AP Statistics
Exam?
The AP Statistics Development Committee, working
‘wich content experts ac Educational Testing Service
(ETS), is responsible for creating the exam. This
committee is made up of eight teachers from secondary
schools, colleges, and universities in different pacts of
the United States. The members provide different
perspectives: AP high school teachers offer valuable
advice regarding realistic expectations when matters of
content coverage, skills required, and clarity of phrasing
are addressed. On the other hand, college and university
faculty members ensure that the questions are at the
appropriate level of difficulty for an introductory college
course in statistics. Each member typically serves for
three years,
Another person who aids in the development
process is the Chief Faculty Consultant (CEC). He or
she attends every committee meeting to ensure that
the free-response questions selected for the exam can
be scored reliably. You can find out more about the
role of the CFC, and the scoring process in general,
on pages 2-4,
How Do They Develop It?
 
Ir cakes at lease two years to develop each AP Statistics
Exam. The development process is different for
multiple-choice and free-response sections:
Section |
1, Each commitcee member independently writes a
selection of multiple-choice questions based on the
course content outline.
 
2. The committee convenes to review these draft
questions, and eliminates any language, symbols, or
content that may be offensive to major subgroups
of the test-taking population. In addition, statistical
procedures help the committee identify possibly
unfair items.
3. Most of the multiple-choice questions are pretested
in college classes to obtain some estimate of the
question’ level of difficulty.
B
The questions that make it through these screening
processes are assembled according to test specifica-
tions developed by the committee and, after further
editing and checking, comprise Section I of the
AP Statistics Exam.
‘The committee controls the level of difficulty of the
multiple-choice section by including a variety of
questions at different levels of difficuley.Section Il
1. Individual committee members write a selection
of free-response questions based on the course
content outline,
2. The committee reviews and refines draft questions,
and determines which will work well far the AP
Exam. They consider, for example, whether the
questions will offer an appropriate level of difficulty
and whether they will elicit answers that allow
faculty consultants to discriminate among the
responses along @ particular scoring scale, An ideal
question enables the stronger students to demon-
strate their accomplishments while revealing the
limitations of less advanced students.
In the last stage of development, committee mem-
bers give approval to a final draft of all mulciple-choice
and ftee-response questions. This review takes place
several months before the administration of che exam.
Ques
 
n Types
 
‘The AP Exam in Statistics contains a 90-minute
multiple-choice section and a 90-minute fiee-response
section. The two sections are designed to complement
each other and to meet the overall course objectives
and exam specificasions.
Multiple-choice questions are obviously useful for
‘measuring the breadth of content in the curriculum. In
addition, they have three other strengths:
1, They are highly reliable. Reliability, ot the lkeli-
hood that candidates of similar ability levels taking
a different form of the exam will receive the same
scotes, is controlled more effectively with multiple-
choice questions than with free-respanse questions.
2. They allow the Development Committee to
clude a selection of questions at various levels of
difficulty, thereby ensuring that che measurement
of differences in students’ achievement is optimized.
For AP Exams, the most important distinetions
are between students earning the grades of 2 and 3,
and 3 and 4. These distinctions are usually best
ed by using many questions of middle
 
  
diffculry
 
3, They allow the CFC co compare the ability evel of
the current candidates with those from another
year. A number of questions from an earlier exam
are included in. che current one, thereby allowing
comparisons to be made between the scores of the
earlier group of candidates and the current group.
‘This information, along with other data, is used by
the CEC w establish AP grades that reflect the
competence demanded by the Advanced Placement
Program, and that compare with earlier grades,
Free-response questions on the AP Sratistics Exam
require scudents to use theie analytical and ongar
tional skills to formulate cogent answers. They also
allow students:
 
1. To relate different content areas as they formulae
a complete solution to a statistics or probabilicy
problem.
To present uncommon yet correct responses.
3. To demonsteate their mastery of stati
of creativity.
 
ics by a show
Free-response and multiple-choice questions are
analyzed both individually and collectively after each
administration, and the conclusions are used to improve
the following year’s exam.
Scoring the Exam
 
Who Scores the Statistics Exam?
The people who score the fie-response section of the
AP Statistics Exam ace known as “faculty consultants.”
‘These faculty consultants are experienced statistics
instructors who either teach the AP course in a high
school, or the equivalent course at college or univer-
sity. Great care is taken to get a broad and balanced
group of teachers. Among the factors considered.
before appointing someone to the role are school
locale and setting (urban, rural, etc.), gender,
cechnicity, and years of teaching experience. If you are
interested in applying to be a faculty consultant at a
fueure AP Reading, you can complete and submit an
‘online application in the “Teachers” section of the
AP website (wwu.collegeboard.org/ap), or request a
printed application by calling (609) 406-5384.
 
[2]During the second week of June 1997, 56 teachers
of statistics, about half from colleges and half from high
schools, gathered at the College of New Jersey, Trenton.
Among these teachers, eight were invited to serve as
“rable leaders” and to come to the Reading two days
carly to help lead the effort. The remaining 48 readers
were divided into eight teams of six readers each, with
cach teazm ceporting to one table leader. Under the
guidance of the Chief Faculty Consultan, the table
leaders had responsibility for organizing the details of
the Reading and conveying information to the readers
in the respective teams.
Ensuring Accuracy
The primary goal of the scoring process is co have each
faculty consultant score his or her set of papers Fairly,
uniformly, and to the same standard as the other faculty
consultants, This is achieved chrough the creation of
detailed scoring guidelines, the thorough raining of all
faculty consultants, and various “checks and balances”
applied throughoue che AP Reading
How the Scoring Guidelines are Created
1. Before the AP Reading, the CEC prepares a draft
of the scoring guidelines for each free-response
question. In the case of Statistics, 2 5-point scale
(0-4) was used. A score of 0 means the student
received no credit for the problem.
2. The CRC, question leaders, table leaders, and ETS
content experts meet atthe Reading ste a few days
before the reading begins. They review and revise che
draft scoring guidelines, and test them by pregrading
randomly selected student papers. The Statistics
leaders were satisfied thar chis method allowed for
consistent scoring of open-ended questions for which
many different approaches could be equally correct
and for which a written statement on assumptions
and conclusions was required. If problems or
ambiguities become apparent, the scoring guide-
lines are revised and refined until a final consensus
is reached,
3, The CEG, question leaders, and table leaders
conduct training sessions for each fiee-response
question, which are attended by all the faculty
consultants who are scoring that question.
Training Faculty Consultants to Agply the
Scaring Guidelines
Since the training of the faculty consultants isso vital
in ensuring that students receive a grade that accurately
reflects their performance, the process is chorough:
1. The faculty consultants read sample papers that
have been pregraded (see above). These samples
reflect all levels of abilicy.
Each group of faculry consultants then compares
and discusses the scores for the samples, based on
the scoring guidelines.
3. Once the faculty consultants asa group can apply
the standards consistently and without disagree-
ment, they begin reading in teams of two. Each
team member scores a packet of five papers and
then exchanges the examinations for a second
reading. Scores and differences in judgmenc are
discussed uncil agreement is reached, with the
question leaders, the rable leaders, or the CRC
acting as arbitrator when needed.
4, After team shows consistent agreement on is
scores, ies members proceed to score individually
Faculty consultants are encouraged to seek advice
from each other, the question leaders and table
leaders, or the CFC when in doubt about a score.
Acstudent response that is problematic receives
multiple readings and evaluations.
Maintaining the Scoring Guidelines
A potential problem is thac a faculty consultant could
give an answer a higher o lower score than it deserves
because the same student has performed well or poorly
con other questions. The following steps are taken t0
prevent this so-called “halo effect”
Each question is read by a different faculey
consultant;
All scores given by other faculty consultants are
completely masked; and
@ The candidate’ identification information is
covered, Using these practices permits each faculty
consultant to evaluate free-response answers
without being prejudiced by knowles
individual candidates.Here are some other methods that help ensure that
everyone is adhering closely to the scoring guidelines:
The entire group discusses pregeaded papers exch
morning, and as necessary during the day.
@ Table leaders re-read (back read) a portion of the
student papers from each of the readers in chat
leader's eam, This approach allows each leader to
guide his or her readers toward appropriate and
consistent interpretations of che rubrics,
 
& Faculty consultants are paiced, so that every reader
has a partner to check consistency and to discuss
problem cases with; rable leaders were also paired
up to help each other on questionable calls.
The CFC and the question leaders monitor use of
the full range of the scoring scale for the group and
for each faculty consultant by checking daily graphs
of score distributions.
Preparing Students for the Exam
 
 
The AP Statistics course is designed to be comparable to
atypical non-calculus-based introductory statistics course
taught in a college or university department of math-
cematics, mathematical sciences, or statistics. The outline
of topies for the course was developed after careful
seudy of the components of modern statistics courses
taught in these venues. There are a wide variety of
statistics courses taught with emphasis in business,
social sciences, engineering, or other concentrations
that would nor necessarily be equivalent to the AP
course, although there should be considesable overlap.
Thus, it is important that the student and AP teacher
understand the type of college course toward which
the AP course is directed.
As outlined in the AP Statistics Course Description,
the course emphasizes four main areas:
@ Exploring Data: observing patterns and deparcures
from patterns
Planning a Study: deciding what and how to
measure
| Anticipating Patterns: producing models using
probability and simulation
@ Statistical Inference:
 
firming models
 
Compared to most equivalent college cousses, the
AP syllabus is actually much more ambitious. The more
comprehensive outline can be accommodated in the
[AP cousse because it usually runs for a full academic yeas,
as opposed to the typical single semester devoted to the
course at the college level. The extra topics and depth of
coverage to which the AP student is exposed prepares
‘that student for a wide variety of college courses found
within the mathematical sciences arena.
‘The AP Statistics course emphasizes modern data
analysis (defining a problem, designing a data coll
plan, collecting data, analyzing data, and making
decisions through data) rather than the theory of
statistics or probability. Technology, then, has a key role
to play in the learning of the subject since the computer
is the chief tool for modern data analysis. Students
should have some experience wish statistical sofware
and be able co read standard computer printouts.
Because a computer cannat be used on the exam, each
student is expected to have access to a graphing caleula-
tor with standard statistical functions, Some caleula-
tions may be required on the exam.
In the final analysis, sradents must have completed a
serious course in the basics of modern statistical meth-
oods and practice, with some exposure «© probability as it
is used to describe statistical discributions and some
experience with modern statistical technology. Even
with a full year to master this material, many students
will find this isa difficult agenda to complete. The
developers of the AP Statistics program, knowing rhat
the course is quite demanding, have tried to alleviate
some of the pressure by tying key ideas to current
strands in statistics that are developing throughout the
K-12 mathematics curriculum. The basics of exploring,
data can begin in the elementary grades, for example,
and simulation as a tool to understand statistical
distributions can begin in the middle grades. In chat
way, statistics becomes a way of using dara to salve
problems with consistent and repeating themes
throughout the student’ K-12 experience. Viewed in
these terms, the AP syllabus does not seem as imposing
asat firs sight.Teacher Support
 
‘There are a number of resources available to help
teachers prepare their students — and themselves —
for the AP course and exam
AP workshops and summer institutes. New.
and experienced teachers are invited to attend work
shops and seminars to learn the rudiments of teaching
an AP course as well as che latest in each course's
expectations. Sewsions of one day to several weeks in
length are held year-round. Dates, locations, topics, and
fees arc available from the College Board’s Regional
Offices (see the inside front cover of this booklet), in
the publication Graduate Summer Courses and Institutes,
or in the “Teachers” section of our website (see below).
AP's comer of College Board Online® You can,
supplement your AP course and preparation for the
exam with plentiful advice and resources from our AP
web pages (wrnw.collegeboard.org/ap)
Online discussion groups. The AP Program has
developed an interactive online mailing list for each AP
subject. Many AP teachers find this free resource to be
an invaluable tool for sharing ideas with colleagues on
syllabi, course texts, teaching rechniques, and s9 on,
and for discussing other AP issues and topics as chey
arise. To find our how co subscribe, go to the “Teachers”
section of our website.
 
AP publications and videos. See the Appendix for
descriptions ofa variety of useful materials for teachers.
‘OF particular interest is the publication thar comple-
ments this Released Exam - the Packet of 10. Teachers
can use these multiple copies of the 1997 AP Statistics
Exam, which come with blank answer sheets, 0
simulate a national administration in their classroom.
AP videoconferences. Several videoconferences are
held each year so tha AP teachers can converse elec-
tronically wich the high school and college teachers who
develop AP courses and exams. Schools that participate
in the AP Program are notified of the time, date, and
subject of the videoconference in advance. Or, you can
contact your Regional Office for mare information,
Videotapes of each conference are available shortly after
the event; see the Appendix for ordering information.The 1997 AP Statistics Examination =
Exam Content and Format
Purpose of the Exam
Giving a Practice Exam
1 Inscructions for Administering the Exam
@ The Exam
Exam Content and Format
 
The 1997 AP Statistics Exam contained questions from
all four major areas of concent (exploring data, planning
a study, probability, and statistical inference) in both the
35-question objective (multiple-choice) and 6-question
Free-response parts. Each part contributed 50% to the
composite score.
The six free-response questions covered the areas
of dara exploration, study design, probability, statistical
inference and fitting models to data. The first five
were short-answer questions; the sixth was a longer
investigative task carrying 25% of the score for the
fSree-response section.
Question 1. The data exploration question involved
cumulative proportions, which is not adequately
covered in most standard textbooks, but was based on
relatively simple daca sets and asked for summary
statistics and interpretations well within the content
outline for this course.
Question 2, The design question asked students t0
explain how they would sev up an experiment, and a
complete response required explanation of both block-
ing and randomization,
‘Question 3. The probability question required some
knowledge of conditional probability bur the answers
could be found through logical thinking without appeal
«0 formal theorems on probability.
Questions 4 and 5. The two inference questions were
buil around scenarios that required the comparison of
‘wo proportions and the analysis of che mean of paired
differences, respectively. These questions were similar to
the typical questions found in textbooks and, hence,
    
generated extensive responses from almose all students
taking the exam,
Question 6. The investigative task required the
student t0 critique models already fit to a ser of daca
and then to find a model that did not have the weak-
nesses of those presented. For this question, students
possessing skill wich a graphing calculator may appear
to have had some advantage over others, but this was
offier by a grading scheme that gave as much weight to
4 good explanation as to clever calculation.
The scoring guidelines for the free-response ques
tions, and sample student responses, can be found in
Chapter IIL
Purpose of the Exam
The purpose of che AP Statistics Exam is to allow
students to demonstrate mastery of the concepts and
techniques of modern statistics at the level of a non-
calculus-based inssoductory college course. Such a
course is required or recommended for most college
majors and, in fact, the numbers of scudents taking
introductory statistics is rapidly approaching the
number taking calculus. Ifa student earns a satisfactory
AP grade and consequently credit for the equivalent
college course, chen thae student may have the opportu-
nity 10 take a second statistics course that will provide
the special emphases requited of his or her major. Even
if no second course is in the offing, the student is
prepared to confront statistical issues much earlier in
the college progeam than miight otherwise be the case.
Scudents who take the AP Statisties course but ope not
to take the exam still have the advantage of background
knowledge that will serve them well when they do take
statistics as part of their college pragsam of studies.
The above discussion begs the question, “what is
the purpose of such a college course?” Students of
roday, the workforce of tomorrow, live in an informa-
tion age. Most aspects of their lives, from the faod
available to eat to che medications available for an
illness, from decisions about buying a car co decisionsabout choosing an occupation, from choices of political
candidates to choices of movies or TV programs, are
regulated by data that they or someone else has col-
lected and analyzed, for good or ill. Therefore it
behooves students to learn something about daca
collection and analysis so that they can enjoy life as
informed citizens and productive workers. Numeracy,
being able to “read” and understand data, is now as
important as literacy. In addition to the advantages for
life enhancement, introductory statistics provides the
basis for the deeper study of the subject required in
many fields, including medical science, biology; engi-
neering and psychology. AP Statistics is a good option
for any student, but particularly for a student who plans
farcher study in a quantitative field.
Giving a Practice Exam
 
‘The following pages contain the instructions, as printed
in the 1997 Coordinator's Manual, for administering
the AP Statistics Exam. Following these instructions is a
copy of the 1997 Statistics Exam. If you wish to use this
released exam to test your students, you may wish to use
the instructions to create an exam situation that closely
resembles @ national administration. If so, read only the
rections in the boxes to the students; all other instruc-
tions are for the person administering the test and need
not be read aloud. Some instructions, such as those
referring to the date, the time, and page numbers, are
no longer relevant; please ignore them.
Another publication that you might find useful is che
so-called “Packets of 10.” They are just chat: packets of en
of the 1997 AP Statistics Exam, each with a blank answer
sheet. For ordering information, sce the Appendix.Instructions for Administering the Exam
 
 
 
the Sites Beaman Betas eg ie xa
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carats you may ive he candidate one fom
your supply Ifa candidate does not want 0 use the ||
verlag you have proved ave him or her we
 
 
 
 
under “Calculators” in the “Administering the Exam”
section. Candidates may have one or two calculators,
fon their desks while Sections T and I are being
administered. Candidates with Hewlett Packard 48
Series graphing calculators may use cards designed
for use with these calculators, Proctors should make
sure infrared ports (Hewlett Packard) are not sarroreces
each other.
Section I of your test contains only nuitiple-
choice questions. Questions in Section I are
numbered 1 through 35, Mark your responses on
page 2of your answer sheet. You are not to open the
sealed Section IT booklet until you are told to doso.
Remember, when you come to the end of the
multiple-choice questions, there will be answer
ovals left on your answer sheet. The time for
Section 1 is 90 minutes. Scratch paper is not
| allowed but you may use the margins of your
Section I booklet. Are there any questions?
 
 
 
Answer all questions regarding procedure. Set your watch
at 12:59. When it reads exactly 1:00 sa
 
 
‘Open your Section I booklet and begin.
While the candidates are working, you and your proctors
 
should make sure they are marking their answers on page 2
of the answer sheet in pencil. The color of page 2 of the
answer sheer is purple (blue for late administrations).
Calculator memories need not be cleared before or after
the exam, Calculators may not be shared. Communication
between calculators is prohibited during the exarn. Proctors
should walk around and make sure Hewlett Packard
calculators’ infrared ports are not facing each other
p> Undertned instructions should not be read aloud during
‘a hte administration,
AT 2:
 
If you are using these instructions. == scheduled
exam, disregard all instructions marked with an arrow (>),
Ifyouare using these instructions for alate administration,
read them carefully beforehand, keeping in mind the
following: 1) directions marked with an arrow (B>) apply
only to proctors giving late administrations; 2) underlined.
instructions should nor be read to candidates during a late
administration; 3) dates and days to be read aloud during a
late administration should be adjusted as necessary.
‘After completing the general instructions beginning on
page 31, say:
 
 
0 PM —
Stop working, Close your exam booklet. Make
sure you printed your name, last name first, on the
{cont cover of your Section I booklet. ... Do not
insert your answer sheet in the booklet. I will now
collect the answer sheets.
After you have collected an answer sheet from every
candidate, say
It is Tuesday afternoon, May 6, and you will |
| be taking the AP Statistics Exam, You may not use
 
reference materials or unapproved calculators
during this examination, If you brought any with
| ‘you, put them under your chair. Print your name,
 
last name first, on the front cover of the unsealed
Section I booklet. . .. Read the directions on the
back of the booklet. When you have finished, look
_ _
ee Seal the Seton 1 bookie with the three seals]
you have provided the information requested and
‘marked your responses correctly. ... Your answer
 
provided. Pull off each seal from the backing sheet
 
the area marked “PLACE SEAL HERE.” Fok
Shectilesonedby machine orn |
‘may alter your grade. Mark your responses on
| page 2 of your answer sheet (one response per |
| and press it on the front cover so it just covers
‘over the open edge and press it to the back cover.
Use one seal for each open edge. Be careful not to
let the seals touch anything except the marked
question). Be certain the number of the question
areas...
you are answering matches the number on the
answer sheet, Use only no. 2 pencils to mark your
answers on Section I. Your answer marks must be
dark and fill the oval completely. Stray marks and
smudges may be read as answers by the machine
so erase carefully and completely.
 
Be sure
Collect the sealed Section 1 exam booklets.
yon receive one from every candidate; then give your
ibreak instructions. A five-minute break is permitted,
Students may talk, move about, or leave the room together
to get a drink of water or go to the rest room. Caleulators
‘must remain turned off and must NOT be taken from
the examination room. (See “Breaks During the
Examination”)
 
D> Late Testing Only
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SECTION I
Time— 1 hour and 30 minutes
Number of questions —35
Percent of total grade—50
Section I of this examination contains 35 multiple-choice questions. Please be careful to fill in only the ovals
‘that are preceded by numbers 1 through 35 on your answer sheet.
General Instructions
DO NOT OPEN THIS BOOKLET UNTIL YOU ARE INSTRUCTED TO DO SO.
INDICATE ALL YOUR ANSWERS TO QUESTIONS IN SECTION | ON THE SEPARATE ANSWER SHERT
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that the previous mark is erased completely.
 
Example:
What te artes mean ofthe numbers Sample Answer
1
Mt Ms O38
10 1
OF Oz
Many candidates wonder whether or not to guess the answers to questions about which they are not certain. In
this section of the examination, as a correction for haphazard guessing, one-fourth of the number of questions
you answer incorrectly will be subtracted from the number of questions you answer correctly. It is improbable,
therefore, that mere guessing will improve your score significantly; it may even lower your score, and it does
take time. If, however, you are not sure of the best answer but have some knowledge of the question and are
able 10 climinate one oF more of the answer choices as wrong, your chance of answering correctly is improved,
and iC may be 0 your advantage to answer such a question
 
Use your time effectively, working as rapidly as you can without losing accuracy. Do not spend too much time
cn questions that are too difficult. Go on to other questions and come back zo the difficult ones later if you have
time. It is not expected that everyone will be able (0 answer all the multiple-choice questions.
Formulas begin on page 12.
‘Questions begin on page 15.
“Tables begin on page 34.
CCopysghe © 1997 by Educational Testing Service and College Entrance Examination Board ll ight served
11Formulas
() Descriptive Statistics
(m4 =I) si +(m ~1)s5
(m=1)+(%2=1)
Sp
Sado thx(I) Probability
PAU B)= P(A)+P(B)- (ANB)
P(AQB)
MA
E(X)= py = Lapp;
Var(X)= 07 = D(a ~ Hx)
IfX has a binomial distribution with parameters n and p, then:
roc==[f)pta- pt
 
IfX has a normal distribution with mean p. and standard deviation 6, then:
be =h
o
op=
vn(HM) Inferential Statistics
. , estimate —
Standardized test statistic: imate — parameter
standard deviation of estimate
Confidence interval: estimate + (critical value) + (standard deviation of estimate)
Single-Sample
 
 
 
 
 
 
 
   
 
 
 
 
Proportion
Two-Sample
Difference of means 2 ge
{unequal variances) C1 4, 92
m M2
Difference of means Tt
(equal variances) Olay Say
Difference of proportions i 1
(unequal variances) it mn Po alcnl
Difference of proportions fap fo
(equal variances) P(l-P) yn tn
 
 
 
 
served 2
Chi-square test statistic = y, Cnet epeeSTATISTICS
SECTION
Time—1 hour and 30 minutes
Number of questions—35
Percent of total grade—50
Directions: Solve each of the following problems, using the available space for scratchwork. Decide which
is the best of the choices given and fill in the corresponding oval on the answer sheet. No credit will be
given for anything written in the test book. Do not spend too much time on any one problem,
1. USA Today reported that speed skater Bonnie Blair had “won the USA's heart,” according to a USA
Today/CNNIGallup poll conducted on the final Thursday of the 1994 Winter Olympics. When asked
who was the hero of the Olympics, 65 percent of the respondents chose Blair, who won five gold
medals. The poll of 615 adults, done by telephone, had a margin of error of 4 percent. Which of the
following statements best describes what is meant by the 4 percent margin of error?
(A) About 4 percent of adults were expected to change their minds between the time of the poll and
its publication in USA Today
(B) About 4 percent of adults did not have telephones.
(C) About 4 percent of the 615 adults polled refused to answer.
(D) Not all of the 615 adults knew anything about the Olympics.
(E) The difference between the sample percentage and the population percentage is likely to be jess
than 4 percent.
 
 
CCR Oa ae Ct
  
 
152. An automobile manufacturer claims that the average gas mileage of a new model is 35 miles per gallon
(enpg). A consumer group is skeptical of this claim and thinks the manufacturer may be overstating the
average gas mileage. If [L represents the true average gas mileage for this new model, which of the
following gives the null and alternative hypotheses that the consumer group should test?
(A) Hy:
Hi,
®) Hy:
Hy:
© Hy
it
(D) Hy:
Hy
(E) Hy
H:
H< 35 mpg
1 2 35 mpg
S35 mpg
> 35 mpg
b= 35 mpg
b> 35 mpg
H = 35 mpg
a < 35 mpg
w= 35 mpg
ht # 35 mpg
 
3. A magazine has 1,620,000 subscribers, of whom 640,000 are women and 980,000 are men. Thirty
percent of the women read the advertisements in the magazine and 50 percent of the men read the
advertisements in the magazine. A random sample of 100 subscribers is selected. What is the expected
number of subscribers in the sample who read the advertisements?
(A) 30
B) 40
(©) 42
(D) 50
(E) 80
TCR a amt4. A manufacturer makes lightbulbs and claims that their reliability is 98 percent. Reliability is defined to
be the proportion of nondefective items that are produced over the long term. If the company’s claim is
correct, what is the expected number of nondefective lightbulbs in a random sample of 1,000 bulbs?
 
(A) 20
(B) 200
(©) 960
(D) 980
(E) 1,000
 
5. When a virus is placed on a tobacco leaf, small lesions appear on the leaf. To compare the mean
number of lesions produced by two different strains of virus, one strain is applied to half of each of
8 tobacco leaves, and the other strain is applied to the other half of each leaf. The strain that goes on
the right half of the leaf is decided by a coin flip. The lesions that appear on each half are then
counted. The data are given below.
Leaf Strain? Strain 2
1 31 18
2 20 7
3 18 14
4 7 HW
5 9 10
6 8 1
7 10 3
8 7 6
What is the number of degrees of freedom associated with the appropriate t-test for testing to see if,
there is a difference between the mean number of lesions per leaf produced by the two strains?
(A) 7
(B) 8
© i
(D) 14
(E) 16
GO ON TO THE NEXT PAGE
176. Which of the following is a criterion for choosing a t-test rather than a z-test when making an infer-
ence about the mean of a population?
(A) The standard deviation of the population is unknown.
(B) The mean of the population is unknown,
(C) The sample may not have been a simple random sample.
(D) The population is not normally distributed.
{E) The sample size is less than 100.
 
7. A certain county has 1,000 farms. Corn is grown on 100 of these farms but on none of the others. In
order to estimate the total farm acreage of corn for the county, two plans are proposed.
Plan I: (a) Sample 20 farms at random.
(b) Estimate the mean acreage of corn per farm in a confidence interval.
(c) Multiply both ends of the interval by 1,000 to get an interval estimate of the total.
Plan II: (a) Identify the 100 corn-growing farms
(b) Sample 20 corn-growing farms at random.
(c) Estimate the mean acreage of corn for corn-growing farms in a confidence interval.
(4) Multiply both ends of the interval by 100 to get an interval estimate of the total.
On the basis of the information given, which of the following is the better method for estimating the
total farm acreage of corn for the county?
(A) Choose plan I over plan I.
(B) Choose plan II over plan I
(©) Choose either plan, since both are good and will produce equivalent results
(D) Choose neither plan, since neither estimates the total farm acreage of corn.
(E) The plans cannot be evaluated from the information given.
UO a sama
 
18Eee
8. Which of the following can be used to show a cause-and-effect relationship between two variables?
(A) A census
(B) A controlled experiment
(C) An observational study
(D) A sample survey
(E) A cross-sectional survey
 
9. To check the effect of cold temperature on the elasticity of two brands of rubber bands, one box of
Brand A and one box of Brand B rubber bands are tested. Ten bands from the Brand A box are placed
in a freezer for two hours and ten bands from the Brand B box are kept at room temperature. The
amount of stretch before breakage is measured on each rubber band, and the mean for the cold bands
is compared to the mean for the others. Is this a good experimental design?
(A) No, because the means are not proper statistics for comparison.
(B) No, because more than two brands should be used
(C) No, because more temperatures should be used.
(D) No, because temperature is confounded with brand,
(B) Yes
GO ON TO THE NEXT PAGESet A
 
 
 
 
 
 
SetB = ———| —
 
 
 
10 20 30 40 50
10. The boxplots above summarize two data sets, A and B. Which of the following must be true?
I. Set A contains more data than Set B.
IL. The box of Set A contains more data than the box of Set B.
TIL. The data in Set A have a larger range than the data in Set B.
(A) Lonly
(B) I only
(©) Land II only
(D) Mand IIT only
(©) 1M, and I
 
11, The XYZ Office Supplies Company sells calculators in bulk at wholesale prices, as well as individu-
ally at retail prices. Next year’s sales depend on market conditions, but executives use probability to
find estimates of sales for the coming year. The following tables are estimates for next year’s sales.
  
WHOLESALE SALES
Number Sold 2,000 5.000 10,000 20,000
Probability or 03 04 02
RETAIL SALES
Number Sold 600 1,000 1,500
Probability 04 0s 0.1
What profit does XYZ Office Supplies Company expect to make for the next year if the profit from
each calculator sold is $20 at wholesale and $30 at retail?
(A) $10,590
(B) $220,700
(©) $264,750
(D) $833,100 OR Gan ada \c3
 
(B) $1,002,50012. The heights of adult women are approximately normally distributed about a mean of 65 inches with a
standard deviation of 2 inches. If Rachael is at the 99th percentile in height for adult women, then her
height, in inches, is closest to
(A) 60
(B) 62
© 68
) 70
(E) 74
 
13. Joe and Matthew plan to visit bookstore. Based on their previous visits to this bookstore, the proba-
bility distributions of the number of books they will buy are given below
Number of books
Joe will buy 0 I
 
Probability 050 0.25 0.25
Number of books
Matthew will buy 0 1 2
Probability | 0.25 0.50 0.25
Assuming that Joe and Matthew make their decisions independently, what is the probability that they
will purchase no books on this visit to the bookstore?
(A) 0.0625
(B) 0.1250
(C) 6.1875
(D) 0.2500
(E) 0.7500
Cn Cam
 
21Job NoJob Total
 
 
 
 
 
Juniors [13 5 18
Seniors | 13 26 39
Total 26 31 37
 
 
 
 
 
14, A survey of 57 students was conducted to determine whether or not they held jobs outside of school.
The two-way table above shows the numbers of students by employment status (job, no job) and class
Guniors, seniors). Which of the following best describes the relationship between employment status
and class?
(A) There appears to be no association, since the same number of juniors and seniors have jobs.
(B) There appears to be no association, since close to half of the students have jobs.
(C) There appears to be an association, since there are more seniors than juniors in the survey.
(D) There appears to be an association, since the proportion of juniors having jobs is much larger than
the proportion of seniors having jobs.
(E) A measure of association cannot be determined from these data
 
3 CSC«SSSC«SSCS
15. Which of the following is the best estimate of the standard deviation of the distribution shown in the
figure above?
(A) 5S
(B) 10
(C) 30
(D) 50
(E) 60
 
   
Ce an aa
2216. Ten students were randomly selected from a high school to take part in a program designed to raise
their reading comprehension. Each student took a test before and after completing the program. The
mean of the differences between the score after the program and the score before the program is 16. It
was decided that all students in the school would take part in this program during the next school year.
Let 11, denote the mean score after the program and H, denote the mean score before the program
for all students in the school. The 95 percent confidence interval estimate of the true mean difference
for all students is (9, 23). Which of the following statements is a correct interpretation of this confi-
dence interval?
 
(A) by > Hp with probability 0.95.
(B) Lt,  14, the sample result is quite likely.
(E) For any 1, and py with 9 < (1, — Hy) < 23, the sample result is quite likely.
 
17. Gina’s doctor told her that the standardized score (z-score) for her systolic blood pressure, as compared
to the blood pressure of other women her age, is 1.50. Which of the following is the best interpretation
of this standardized score?
(A) Gina’s systolic blood pressure is 150.
(B) Gina’s systolic blood pressure is 1.50 standard deviations above the average systolic blood pressure
of women her age.
(C) Gina’s systolic blood pressure is 1.50 above the average systolic blood pressure of women her age.
(D) Gina’s systolic blood pressure is 1.50 times the average systotic blood pressure for women her age.
(E) Only 1.5% of women Gina’s age have a higher systolic blood pressure than she does.
 
Cee al am ti18, The Physicians’ Health Study, a large medical experiment involving 22,000 male physicians, attempted
to determine whether aspirin could help prevent heart attacks. In this study, one group of about 11,000
physicians took an aspirin every other day, while a control group took a placebo. After several years, it
was determined that the physicians in the group that took aspirin had significantly fewer heart attacks
than the physicians in the control group. Which of the following statements explains why it would not
be appropriate to say that everyone should take an aspirin every other day?
1. The study included only physicians, and different results may occur in individuals in other occu-
pations.
II. The study included only males and there may be different results for females.
TM. Although taking aspirin may be helpful in preventing heart attacks, it may be harmful to some other
aspects of health.
(A) Lonly
(B) only
(©) Wonly
(D) I and TI only
(E) 1,11, and Ut
CO an 2 aa.|
24Questions 19-20 refer to the following information,
Every Thursday, Matt and Dave's Video Venture has “rofl-the-dice” day. A customer may choose to roll
two fair dice and rent a second movie for an amount (in cents) equal to the numbers uppermost on the dice,
with the larger number first. For example, if the customer rolls a two and a four, a second movie may be
rented for $0.42. If a two and a two are rolled, a second movie may be rented for $0.22. Let X represent
the amount paid for a second movie on roll-the-dice day. The expected value of X is $0.47 and the stan-
dard deviation of X is $0.15.
19. If a customer rolls the dice and rents a second movie every Thursday for 20 consecutive weeks, what is
the total amount that the customer would expect to pay for these second movies?
(A) $0.45
(B) $0.47
(C) $0.67
(D) $3.00
(E) $9.40
 
20. If a customer rolls the dice and rents a second movie every Thursday for 30 consecutive weeks, what is
the approximate probability that the total amount paid for these second movies will exceed $15.00 ?
(A) 0
(B) 0.09
(© 0.14
(D) 0.86
(E) 0.91
Cea 2 a(t
2521. A company wanted to determine the health care costs of its employees. A sample of 25 employees
were interviewed and their medical expenses for the previous year were determined. Later the company
discovered that the highest medical expense in the sample was mistakenly recorded as 10 times the
actual amount. However, after correcting the error, the corrected amount was still greater than or equal
to any other medical expense in the sample. Which of the following sample statistics must have
remained the same after the correction was made?
(A) Mean
(B) Median
(C) Mode
(D) Range
(B) Variance
22. ‘The back-to-back stem-and-leaf plot below gives the percentage of students who dropped out of schoo!
at each of the 49 high schools in a large metropolitan schoo} district.
 
Schooi Year School Year
1989-1990 | 1992-1993.
ols
9999887/0|566677788899
4444433222211110/1}o0001111222334444
9997766665/1|555666677778
4222100/2|13
8887 6/2
2S e(Ontgsi 2)
766) 35
4
For 1992-1993, 1|2 represents 12%
Which of the following statements is NOT justified by these data?
(A) The drop-out rate decreased in each of the 49 high schools between the 1989-4990 and 1992-1993
school years.
(B) For the school years shown, most students in the 49 high schools did not drop out of high school.
(C) In general, drop-out rates decreased between the 1989-1990 and 1992-1993 school years.
(D) The median drop-out rate of the 49 high schools decreased between the 1989-1990 and 1992-1993
school years.
(E) The spread between the schools with the lowest drop-out rates and those with the highest drop-out
rates did not change much between the 1989-1990 and 1992-1993 school years.
 
TRC a aes23.
Circuit boards are assembled by selecting 4 computer chips at random from a large batch of chips. In
this batch of chips, 90 percent of the chips are acceptable. Let X denote the number of acceptable chips
out of a sample of 4 chips from this batch, What is the least probable value of X 7
(A) 0
(B) 1
© 2
(D) 3
4
 
24.
A random sample of the costs of repair jobs at a large muffler repair shop produces a mean of $127.95
and a standard deviation of $24.03. If the size of this sample is 40, which of the following is an approxi-
‘mate 90 percent confidence interval for the average cost of a repair at this repair shop?
(A) $127.95 + $4.87
(B) $127.95 $6.25
(C) $127.95 £ $7.45
(D) $127.95 + $30.81
{E) $127.95 £ $39.53
 
2725.
Ata college the scores on the chemistry final exam are approximately normally distributed, with a
mean of 75 and a standard deviation of 12. The scores on the calculus final are also approximately
normally distributed, with a mean of 80 and a standard deviation of 8. A student scored 81 on the
chemistry final and 84 on the calculus final. Relative to the students in each respective class, in which
subject did this student do better?
{A) The student did better in chemistry.
(B) The student did better in calculus.
(C) The student did equally well in each course.
(D) There is no basis for comparison, since the subjects are different from each other and are in
different departments.
(E) There is not enough information for comparison, because the number of students in each class is
not known.
 
 
26.
A fair coin is flipped 10 times and the numiber of heads is counted. This procedure of 10 coin flips is
repeated 100 times and the results are placed in a frequency table, Which of the frequency tables below
is most likely to contain the results from these 100 trial
    
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
(A) Number of | Frequency (B) | Number of | Frequency (©) Number of | Frequency
Heads Heads Heads
0 19) 0 9 [0 0
1 12 i 9 1 o
2 9 2 9 2 | 6
E} 6 3 9 3 9
5 1 5 10 5 24
6 3 6 9 6 18
7 5 7 9 7 12
8 8 L 8 9 8 7
14 9 9 9 2
10 2 J 10 9 10 0
(DP) Number of | Frequency | ©) [ Number of | Frequeni
Heads
1 _ 10 0
2 6 i}
4 8 24
5 10 St
|__6 9 22
7 12 1
10. 9 oO27. The student government at a high school wants to conduct a survey of student opinion. It wants to
begin with a simple random sample of 60 students. Which of the following survey methods will
produce a simple random sample?
(A) Survey the first 60 students to arrive at school in the morning.
(B) Survey every 10th student entering the schoo! library until 60 students are surveyed.
(C) Use random numbers to choose 15 each of first-year, second-year, third-year, and fourth-year
students.
(D) Number the cafeteria seats. Use a table of random numbers to choose seats and interview the
students until 60 have been interviewed.
(E) Number the students in the official school roster. Use a table of random numbers to choose
60 students from this roster for the survey.
 
28. There is a linear relationship between the number of chirps made by the striped ground cricket and the
air temperature. A least squares fit of some data collected by a biologist gives the model
j= 25.2 + 3.3 9 10, a sample
from a normal population produces a mean of 13.4, The z-score for the sample is'2.12 and the p-value
is 0.017. Based on these statistics, which of the following conclusions could be drawn?
   
(A) There is reason to conclude that [L > 10.
(B) Due to random fluctuation, 48.3 percent of the time a sample produces a mean larger than 10.
(C) 17 percent of the time, rejecting the alternative hypothesis is in error.
(D) 17 percent of the time, the mean is above 10.
(E) 98.3 percent of the time, the mean is below 10.
 
30. For which of the following distributions is the mean greater than the median?
(A)
0
(@B)
0
©
0
—_ _
 
(D)
®
<——
FN
CRC a aa. (3
30Hew euare
 
 
 
 
 
 
 
 
 
012345678
31. The equation of the least squares regression line for the points on the scatterplot above is,
y = 1.3 + 0.73x. What is the residual for the point (4, 7)?
(A) 2.78
(B) 3.00
(C) 4.00
(D) 4.22
(E) 7.00
 
 
 
32. The distribution of the weights of loaves of bread from a certain bakery follows approximately a
normal distribution. Based on a very large sample, it was found that 10 percent of the loaves weighed
Jess than 15.34 ounces, and 20 percent of the loaves weighed more than 16.31 ounces. What are the
mean and standard deviation of the distribution of the weights of the loaves of bread?
 
 
(A) w = 15.82,
(B) p = 15.82,
(©) p= 1587,
D) w= 15.93,
(E) » = 16.00,
 
COC ans aac33, A 9S percent confidence interval of the form + E will be used to obtain an estimate for an
unknown population proportion p. If 6 is the sample proportion and E is the margin of error,
which of the following is the smallest sample size that will guarantee a margin of error of at most
0.08 ?
 
ia) 25
(B) 100
© 175
(D) 250
(E) 625
 
34, The process of producing pain-reliever tablets yields tablets with varying amounts of the active ingre-
dient. It is claimed that the average amount of active ingredient per tablet is at least 200 milligrams.
The Consumer Watchdog Bureau tests a random sample of 70 tablets. The mean content of the active
ingredient for this sample is 194.3 milligrams, while the standard deviation is 21 milligrams. What is
the approximate p-value for the appropriate test?
(A) 0.012
(B) 0.024
(C) 0.050
(D) 0.100
(E) 0.488
On Cra aa 3
 
3235. A survey was conducted to determine what percentage of college seniors would have chosen to attend
a different college if they had known then what they know now. In a random sample of 100 seniors,
34 percent indicated that they would have attended a different college. A 90 percent confidence interval
for the percentage of all seniors who would have attended a different college is
(A) 24.7% to 43.3%
(B) 25.8% to 42.2%
(C) 26.2% to 41.8%
(D) 30.6% to 37.4%
(E) 31.2% to 36.8%
 
END OF SECTION I
IF YOU FINISH BEFORE TIME IS CALLED, YOU MAY
CHECK YOUR WORK ON SECTION I
DO NOT GO ON TO SECTION II UNTIL YOU ARE TOLD TO DO SO.
33Table entry for zis the
probability lying below 2
 
Probability
  
 
 
 
‘fable A Standard normal probabilities
 
5 or o 08
 
10099
 
 
   
oon r
00% 0098 (009100890087 0084
01250122, 9191160113110
162 01884
   
   
  
31923156
3363235943557 35203483,
4013 3974 393638973859
44044364 ass 4864247
490147614721 46814641Probability
Table entry for zis the
probability lying below
Table A (Continued)
 
 
z | ot 02 3 0s 96 0 08 09
5000 504050805120 S160 519952305279 S319 5359
5398 5438 S478_ 5517553575596 S686 5675 S714 5753
5793 3832 587159105948 598760266064 ©6103. 6141
6179 “621762556293. 633163688406 GAS 4806S
6554 659166286654 67006736. 6772__—6ROB_—_ 844.6879
 
69156950 019° -70sa° 0887193 7157/7190 yaa
ms1 791 T5179 ganas 7a TST. 7549
| 7580. T61l 1673 T0474 TGA 778237852
7881-7910 967-7905 302380518078 81058133,
"R159 8186 8238 Sieh 8289 TIS BO 83658389
B13 8438 MG] 848585088532 85S4— 8577859861
613 (8665-8686 “8708878749 8TI0.—«« 8790810830,
8849 8869 ©—«-8BBB_ 8907 «892580448962 8980-8997 9015
9032 9049-9056 9082-9099 911s. 913191479162 9177
919292079222. 936 925192659279 9282-9306. 9319
9332/7 9MS" 9357 9370-9382) 93049406948 9429 gaan
9452 946394749484 4959505 9S1S. 95255359545
9554 9564 957S_—«9SBZ_—«85SS]_— 939996089616. 962S.— 9633,
2641 964996569664 967196788686 «96936999706
S13 99-96 9732-8738 9TH 8750. 9756-76. 9767
972 ST78.—S«97RB_=«9TBS «97939798 «9803. 9808.-—=—«9812.—BIT
9821 (982698309834 983K 9BAZ~— 985 = 98SO 9854 BRST
9861 9864 986898719875 98TR 98K] 9BR4 98879890
9893 9896-9898 9901 9903-9906 9909991] 99139916.
5918 992099229925. 99279929 993199329934 ‘9936
9938") 9540" “99419943 9943/9946 99489949. 9951 9952
995399559956 99579959 996098619962 9963964
9365 9966 9967996899609) 9071987299738
9974 9971598169977, 997T = gaT8 997999799980 gat
9987 9987 998T 9988-9988 998999899989 99909900.
9990 9991-9991 99919992 9992-9992 999299939993
9593 9903 9984 994 9904 "9904 9904 990599959905,
9995 99959995 9996 9996 19995 9996 999699969997
99979997 999799979997 9997 9997 99979997 ___ 9908
 
 
35Table entry forp and
 
 
 
 
 
 
 
 
 
 
Cis the point * with Probability p
probability p ying
above itand
probability C lying _-~
between -r* and ¢*, =
Table Bt stribution critical values
a [asa OCS SSCS CSS
1 | 10001376 196 3078 631812711589 S12 63651273 «31836366
2 | ‘sis toi 1.38 18862920 43034849 66599251409 22.33 31.60
3 | es 9781250 16382353, 382 34824545881 745310211292
4 | 7 ou 1901533, 232-2776 29993747 60455987173 8.610
5] 779001136176 2015__ asm 2.757 336540324773 5.893 6.369
6 | © 71a 906! 71.134 Pinan a.94s” eh zaa7i aera a.us9! 3700 417 5.208 5.959
7 | "i s96 41194415195 23632517 2998 34894009 ATs 5.408
| 700 889 08139718) 2306 2928963355389 4501 5.0u1
9 703 883 1.100. 1383 ‘1.833 (2.262 2.398 2821 3.250. 3.690 4.297 4.781
10 | 700979 108332 ABI2. Dak asso 26h 36) SRL a 4ST
ni | ‘607876 Loss 1363«1.796 22012398 «271831063497 das 4437
12 | 6s (873, 10831356 1782-2179 23032681 3.055 3428 3.900318
1b] os 870 Lom 13507712460 nae 2650 301233 385242
14 | 692 Rok 10761345761 -214s_ 226 ©2624-2977 332637874140
15 | ool 865 ors 1341753 2131 2.249 2.602 2.947 3.286 3.733 4073
16] 690°) 865° alone 1.337 L746 ?a.na0) 92.038 Pl 2.se3 729m" 252! S96 AIS
I 689 863 1.069. 1.333 1740 2110 2224 2.567 2.898 32 3.646 3.965
1 | 688-862 106743301734 210) 22142552 2a 373613902
19 | 668 861 1.066. 3281292020539 RG] ST9 3.88
20 687 860° 1.0064 1.325 «1.725 2086 2.197 2528 BAS ‘3153 3.552 3.850.
21 | ‘ei 859 106313231721 2080-«2MRDDSIS. 28313135 35273819
mz | ‘86 858 1.061 1321«717«2.074-«2183 25082893119 35053792
a | 685 858 1060 131917142069 2177-2500 2807 3.l0s 3.853.708,
24 | as 571.059 1318 L711 2064 «-2472—«-2a92—«-2.797 3081 34673745
2 | 684 856 Lose 1316 1708 206021672485 2.787 3.078 3.450 «3.725
36 | e349 case: /alasa’ iis) 1.706 2056 72.162") 72479") 2'779"" 3.067! 3.a5 °° 3707
a | oe ass 1087 131s 17032052 2158 247s T3057 3.421 3.680
ag | (83 55 40861313720 2154 a6?) 2763 3.073.408 3.674
29 | 663 AS41055, 1311_«1699 2085-2150 24622759 «33386359
30 | 6838580581310 1697208 2a? 24572750 3.000 3.385 3646
wo | 6s 85110501303, 68420212123. «2423 «270429713307 31
50 | 61 4910471299 1.676 20091092403 2678 2.937 3.261 3.486
co | 67 ‘4810651296 L671 2000-2089 2390-2600 2.015,««3.282 3.460
so | 678 846 1.063 1252 1.664 ©1950 2088234 ©2639-2887 3.195316
100 | 677 ‘s45— 1.062120 1.660 «1988 ©2081 23k ©2625 2B 3178 3.390
wooo | 675 ‘s42 0371282 Noyes ©1962-2056 2330-2581 2.813. «3.083.300
co | 678 BH 103612821685 1960 2058-2326 ©2576 «2807-3081 3.291
50% 60% 10% «Wh ~—«UH~=«C«SS«S=*C«CK SCR «CO «CNS «SBA 09.9
 
Confidence level C
36‘Table entry for p is the point
(22) with probabitty plying
above
Table Cx? critical values
Probability p
 
 
 
 
 
 
 
 
TL Tai probabiy p
af mas Sms OSS —oo_—005
| 12460207 21 sae sm —Sal66)—~—«788~—«ONe—o ada
2 | 277 am 37 615990738782, -921 0609813821520
2 { 4 fe Sm 62s a 935 oak Mae ata? 73
4 | 539 599 e778 94d ade? 1328 1486 Nea? 8A? 2000
s | 6s 729 $12 924 107 a3 1505 167518382051 -22.1
Gf 56 94s ane 289. saas West?) 1855-2025 2046 2410
7 | gor 980 1075 2m 407 te) ies 2028 aor a2
& | 022 nm am B36 551 753 m0 2195 a8
5 | 19 224 1339 Meek 1692) i902 InGk 216725925 a8 2987
19 | 1255 tas ass 599 IRs] 048 ade a2tast9 95912
un | a7 ies 1577 1728198 age ee DAT = 267628733126 Ia
1 | i4as 1581 69918582108 2338 eos 2622283303221
1 | i598 te58 1820 1981 22362424 sa? 716 BADR
1 | iraz Bas 1941 210623682612 2687 891323343 sa SELL
is | teas 1931 2060 2281 25002749 R26 50SE 32804983770 3872
4g faga7) /a0g7 (21790 2386" 2530, 2Ras’ Goea) S00!) 3427) 3646") 925 aL
0 | a ist ase 247) 759 OID gD «BAL 3572 Tas’ oT as
me | 2160 758 16 25992887153 35 ALIS 381 Aha
ww | mm moo 3593 270 302s 8) 361 ASR ome ne? 4897
20 | mas as08 3650. hat uai7) ism 37S? M000 2a sat 4750
a | 2493 2617 766 2962 SST 3548 gad RAIA TB “901
mn | aor 77130 war 30892676 4029 AD 5.20 5051
2 | mie 3843 998 32.01 3517 RO HSIT Los aI 682 5200
aa | 2826 2955 3113 3320 364239364027 2984556 aR she
as | 29a 306 3228 3438 3765 4065 N57 ST 4693 apa 495
26())| fanaa) 31.79. 3349) 9556)-9 93RD! “4192” alas as.64)”)/aR2D." sos 561
a | ass 3291 us? 3674 Holl aI 4696 ak Sa 5786
% | 2O Mos As 2 48h MG HIE SSD 5359 5930
2» | Bn 3518 X68 90 56 as He SAT e073
30. | 34803625) 3199, ozs 437746984796. 5089 SRST. 5633 2.16
a | 4s 4727 aos Stal 5516 59.34 669657769. 7605
so} $633 S816 603s. 6317750142 Wis 949 82.6 956
6 | coos Gas7 71347440 7908 83:30 $838 91959538 9m 1027
so | se13 Gosi 9311 9658 101906 M23. 163190) f2e# 1283
voy | ost yyy 118s 124396 i558 4021443 gpa 1552
 
 
37STATISTICS
SECTION Il
Time—1 hour and 30 minutes
Number of problems —6
Percent of total grade—50
 
GENERAL INSTRUCTIONS
‘There are two parts to this section of the examination. Part A consists of five equally weighted problems that represent
75 percent of the total weight of this section. Spend about 65 minutes on this part of the exam. Part B consists of one
longer problem that represents 25 percent of the total weight of this section. Spend about 25 minutes on this part of the
exam. Since it is not expected that everyone will be able to complete all parts of all problems, you may wish to look
over all the problems before you begin to work. The questions are printed in the booklet and on the green insert: it
may be easier for you to look over all the problems on the insert. Statistical tables and useful formulas are printed
in the green insert. When you are told to begin, open your booklet, carefully tear out the green insert, and start work.
* You should write all work far each part of each problem in the space provided for that part in this booklet. Be sure to write
clearly and legibly. If you make an error, you may save time by crossing it out rather than trying to erase it. Erased or
crossed-out work will not be graded. No credit wen for am shown on the green insert.
© Show all your work. Indicate clearly the methods you use because you will be graded on che correctness of your methods
as well as the accuracy of your final answers. Correct answers without supporting work may not receive credit.
CCopyrighe © 1997 by Eduction Testing Service and College Entanct Examination Board. Al sighs reservedSTATISTICS
SECTION II
Part A
Questions 1-5
Spend about 65 minutes on this part of the exam,
Percent of Section I grade—75
Show all your work. Indicate clearly the methods you use, because you will be graded on the correctness of
your methods as well as on the accuracy of your results and explanation.
AGE DATA
Age | 1900 | 2000
3 | 0.121 | 0.066
15 | 0344 | 0.209
25 | 0540 ] 0.348
35 | 0.700 | 0.480
45 | 0.822 | 0.643
55 | 0.906 | 0.781
65_| 0959 | 0.870
 
 
 
 
 
 
1. The table of data above provides the cumulative proportions for the United States population at
selected ages for the years 1900 and 2000 (projected). For example, 0.344 or 34.4 percent of the popu-
lation was at or under age 15 in 1900, while only 0.209 or 20.9 percent will be at or under age 15 in
the year 2000. The graph below shows the cumulative proportions plotted against age for the years
1900 and 2000 (projected). The data and graph are to be used to compare the age distribution for the
year 1900 with the projected age distribution for the year 2000.
1.0
 
Year 1900)
 
 
 
©
 
 
 
 
 
©
&
 
Cumulative Proportion
©
 
 
 
 
 
 
 
e
&
 
Age
40Ema
(a) Approximate the median age for each distribution
(b) Approximate the interquartile range for each distribution,
(©) Using the results from parts (a) and (b), write a sentence or two for a history textbook comparing
the age distributions for the years 1900 and 2000.
41 |2. A new type of fish food has become available for salmon raised on fish farms. Your task is to design
an experiment to compare the weight gain of salmon raised over a six-month period on the new and the
old types of food. The salmon you will use for this experiment have already been randomly placed in
eight large tanks in a room that has a considerable temperature gradient. Specifically, tanks on the
north side of the room tend to be much colder than those on the south side. The arrangement of tanks
is shown on the diagram below.
Window por Window
—_——
North
 
 
 
 
 
 
 
 
 
 
 
Describe a design for this experiment that takes account of the temperature gradient
 
BOUL a aia
42eae
ESP
3. A laboratory test for the detection of a certain disease gives a positive result 5 percent of the time for
people who do not have the disease. The test gives a negative result 0.3 percent of the time for people
who have the disease. Large-scale studies have shown that the disease occurs in about 2 percent of the
population.
(a) What is the probability that a person selected at random would test positive for this disease? Show
your work.
(b) What is the probability that a person selected at random who tests positive for the disease does not
have the disease? Show your work,
 
   
Oa aaa
434, A random sample of 415 potential voters was interviewed 3 weeks before the start of a state-wide
campaign for governor; 223 of the 415 said they favored the new candidate over the incumbent.
However, the new candidate made several unfortunate remarks one week before the election. Subse-
quently, 2 new random sample of 630 potential voters showed that 317 voters favored the new candi-
date.
Do these data support the conclusion that there was e decrease in voter support for the new candidate
after the unfortunate remarks were made? Give appropriate statistical evidence to support your answer.5. A company bakes computer chips in two ovens, oven A and oven B. The chips are randomly assigned
to an oven and hundreds of chips are baked each hour. The percentage of defective chips coming from
these ovens for each hour of production throughout a day is shown below.
Percentage of Defective Chips
 
   
 
The percentage of defective chips produced each hour by oven A has a mean of 33.56 and a standard
deviation of 5.20. The percentage of defective chips produced each hour by oven B has a mean of
32.44 and a standard deviation of 3.78. The hourly differences in percentages for oven A minus oven B
have a mean of 1.11 and a standard deviation of 4.28.
Does there appear to be a difference between oven A and oven B with respect to the mean percentages
of defective chips produced? Give appropriate statistical evidence to support your answer.
45EEQIF,..<
STATISTICS
SECTION IL
Part B
Question 6
Spend about 25 minutes on this part of the exam.
Percent of Section I grade—25
6. You are planning to self a used 1988 automobile and want to establish an asking price that is competi-
tive with that of other cars of the same make and model that are on the market, A review of newspaper
advertisements for used cars yields the following data for 12 different cars of this make and model. You
‘want to fit a Teast squares regression model to these data for use as a model in establishing the asking
price for your car.
 
 
 
 
{ | ] | |
ae 1990 | 1991 | 1992 ] 1987 | 1993 | 1991 | 1993 | 1985 | 1984 | 1982 | 1986 | 1979
Asking Price
Gn thousands | 6.0 | 7.7 | 88 | 34] 98 | 84) 89 | 15 | 16 | 14 | 20] 10
of dollars)
 
 
 
 
 
 
 
 
 
 
The computer printouts for three different linear regression models are shown below. Model I fits the
asking price as a funetion of the production year, Model 2 fits the natural logarithm of the asking price
as a function of the production year, and Model 3 fits the square root of the asking price as a function
of the production year. Each printout also includes a plot of the residuals from the linear mode! versus
the fitted values, as well as additional descriptive data produced from the feast squares procedure.
 
Model 1.
10.0 a ast,
0.0 a
ee aeg2 ee oo 28 50 7.5 FS
‘The regression equation is Analysis of Variance
Price = -58,1 + 0.719 Year
soURcE DF SS_wS. Foo
Predictor coef stdev trratio Regression 1 121.10 121.20 76.88 0.000
Constant -58.050 7.205 -8.06 0.000 Error 10 15.75 1.58
Year 0.71900 0.08200 © 8.770.000 «total ai 136-88,
251.255 Resq = 88.58
(eeModel 2
 
 
 
 
0.00 *
12 “ “
* -9.40 *
oof
coe oa0 6.60 Tea 80
the regression equation is analysis of Variance
Mapcled eth P SHE Har
Predictor coef seday cratic p soct OF ss skp
Ceeatsne” STifeza PGES AF o.Boo —Regreecion T 5.8550 8.0890 17.77 0 B00
Sears" Gls$63 o.bids2 “35:30 $1000 Befee***°" lo BIMERE. 818432
220.2130 Rags 94.68 Bel oi bce
Model 3
nae oso
- : —s _
an : 0.09 »
im Pare) .
“0.30
80 aa a8 92 Year 0.60 2.20 1.80 2.40 3.007
the regrestion equation 1a anaiysis of variance
SoeoTSEL ITS PT eat.
Predictor cost tomate p somes or 88s kw
ccratcee® SiSfua SST35'° 0 Boo Reoretsion 7.2 7.2 udm o.boo
SEE GR bbe abled 05888 fevserston doar duoedd
5s = 0.2520 Resq = 91.9% ‘Total a 7.8572
aoESE.
(a) Use Mode! ? to establish an asking price for your 1988 automobile.
(b) Use Model 2 to establish an asking price for your 1988 automobile.
()_ Use Model 3 to establish an asking price for your 1988 automobile.
49(d) Describe any shortcomings you see in these three models.
(@) Use some or all of the given data to find a better method for establishing an asking price for your
1988 automobile. Explain why your method is better.
50EXDIF...c
If you need more room for your work, use the space below
END OF EXAMINATION
 
51Ga Answers to the 1997 AP Statistics Examination
Multiple Choice
 
Section I: Multiple Choice Section
 
Blank Answer Sheet Listed below are the correct answers co the multiple-
 
@ Section IT: Free Response choice questions and the percentage of AP candidates
1 Student Preparation for the Exam who answered each question correctly. A copy of the
 Free-Response Questions, Scoring Guidelines, blank answer sheet appears on the following pages for
and Sample Student Responses reference.
® Section II, Part A
Section II, Part B
Section | Answer Key and Percent Answering Correctly
tem Correct Percent Item = Crrect. Percent tom Correct Percent,
oer COMmcu mets (oem)
1 E 866 5 B 739% 2 c 650%
. D 81% 4 D 73% 6 c 55%
3 cl 759% 6 B 83% 2 E 520%
4 D 93% 16 E 69% 28 B 55%
5 A 73% v B 748% 29 A 60%
6 A 680% 18 E 63% 30, A 4696
ie B 61% 19 E 91% 31 A 3%
5 B 80% 20 c 36% 32 D 2%
9 D 80% 2 B 69% 33 c 309%
10 8 87% i A 56% 34 A 53%
1 B 749% 2 A 68% 35 6 6580
R D 76% Et B 70%e e e e ys 1 besa soon openatate isons 20! S100
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| Siscencrms'setoran nine suneusosp eer usemesas | RAALYNDS
 
 
 
 
 
“NOLLVNIWYXa AWIAa Lv Wau SIHLSL31dNI00 — | Wau
eo ° ee ° e 8 6 oo 0
PEEEP UEP PEPE TEEPE EDU EEE EEE TEEPE EEE EEE EEEAdvanced Placement Prograr® PAGE 2
‘THE COLLEGE BOARD
 
 
| a. tats secvion is FORTHE SURVEY QUESTIONS INTHE CANDIDATE PACK. (DO NOT PUT RESPONSES TO
EXAM QUESTIONS IN THIS SECTION.) BE SURE EACH IAAK IS DARK AND COMPLETELY FILLS THE OVAL.
 
1®@OOO 4DOQOOO
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| Bo Nor COMPLETE THIS SECTION UNLESS INSTRUCTED TO DO SO,
R. this answer sheet is forthe French Language, French Literatura, German Language, Spanish Language, of Spanish
Literature Examination, please answer the folowing questions. (Your responses wil not afect your grade)
41, Have you vd or studied for one month oF mere ina county where the
language ofthe exam you are now taking is spoken? O ws No
2, Do you ragulary speak or hear the language at hme? Ow Ono
INDICATE YOUR ANSWERS TO THE EXAM QUESTIONS IN THIS SECTION. IF A QUESTION HAS ONLY FOUR ANSWER.
OPTIONS, DO NOT MARK OPTION (E). YOUR ANSWER SHEET WILL BE SCORED BY MACHINE. USE ONLY NO. 2
PENCILS TO MARK YOUR ANSWERS ON PAGES 2 AND 9 (ONE RESPONSE PER QUESTION), AFTER YOU HAVE
DETERMINED YOUR RESPONSE, SE SURE TO COMPLETELY FILL INTHE OVAL CORRESPONDING TO THE NUMBER OF
THE QUESTION YOU ARE ANSWERING. STRAY MARKS AND SMUDGES COULD BE READ AS ANSWERS, SO ERASE
(CAREFULLY AND COMPLETELY. ANY IMPROPER GRIDDING MAY AFFECTYOUR GRADE.
 
 
 
 
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2 Ihe address gridded above e not comp
 
 
 
 
 
 
 
 
alSection
 
Free Response
Student Preparation for the Exam
The free-response questions, for the most part,
intentionally gave litle ditection as to how the seudenc
‘was to approach the problem and the rubrics were
designed to give credit for any correct method.
However, for inference problems the rubrics required
students to explain the method used along with the
assumptions for the method, and to look carefully at
the data to see if they thought the assumptions were
satisfied. The analysis had to be followed by a clearly
scated correct conclusion, written in che context of
the original question.
‘Many students had difficulty determining whac
method to use, often trying two or three approaches
or mixing approaches in ways that were unclear to
the faculty consultants at the Reading. In addition,
students had difficulty explaining assumptions and
rarely looked at the data to see if assumprions were
satisfied. Conclusions were often poorly written both
in terms of the statistical concepts and the grammar,
Students must learn to view statistical inference as
a process that involves five steps:
Dv
2)
3)
understanding the problem to be solved,
finding an appropriate method,
checking the assumptions for the method against
all the available data,
4)
5)
carrying out the analysis, and
vwriting a clear and correct conclusion in the
context of the original problem,
Student preparation on the basic principles of
blocking and randomization for designed studies was
also quite weak. For question 2, on the design ofan
experiment, many students appeared to be confused
about whas constituted the treatments and what
consticuted che experimental units, Among those who
seemed to grasp this idea, many did not understand
that blocking is dhe best way to reduce variation among
the experimental units oF got confused about how to
block appropriately. In addition, many did not under-
stand hac randomization is necessary to reduce bias and
to allow probability-based methods of analysis to be
used after the data are collected
  
In summary, the examination contained a fairly easy.
multiple-choice section and a challenging free-response
section. The questions in the larcer appeared to be fait
in light of the Course Description, bur many students
were not adequately prepared to explain and defend
methods used and to verite clear conclusions reflecting
both good statistics and good writing.
Free-Response Questions, Scoring
Guidelines, and Sample Student Responses
‘The answers presented here are actual student
responses to the six free-response questions on the
1997 AP Statistics Examination. The scudencs gave
permission to have their work reproduced at the time
they took the exam. These responses were read and
scored by the leaders and faculty consultants assigned
to each particular question and were used as sample
responses for the training of faculty consultants during
the AP Reading in June 1997. The actual scores that
these students received, as well asa brief explanation of
why, are indicated.
 
 
57Question 1 Scoring Guidelines
 
4 Complete Response
Correctly uses the graph or (informally) interpolates in
the table co approximate the medians and quartiles. The
numerical values must make practical sense within
the context of the problem.
Approximates medians for 1900 to be about 23 or 24
and for 2000 about 35 or 36.
Approximates the interquartile ranges for 1900 to be
about 40 - 12 = 28 and for 2000 about 54 - 18 = 36.
May not caleulate the IQR but gives a clear indication
in che writing that che distance berween the quartiles is
a measure of spread.
States clearly that the U.S. age distribution will shift
toward larger values for 2000 as compared to 1900,
wich greater variability in 2000. The statement is
consistent with the numerical results from parts (a) and.
(b) and is written in such a way that it would be
understood by the general population.
Sample 1
3 Substantial Response
Approximates medians and interquartile ranges neatly
correctly from the graph or the table. Need not
calculate the IQR if there is some indication that the
quartiles can measure variability.
States clearly that the U.S. age distribution will shift
toward larger values for 2000 as compared ro 1900, but
‘may not specifically mention the increase in variabilcy
2 Developing Response
Gives a poor approximation for the medians or
interquartile ranges, but seems to have some
understanding of what these measures represent.
Or, provides at lease a weak but correct statement on.
the nature of the changing populations.
1 Minimal Response
Indicates some understanding of at least one of the
three parts of the question.
 
(2) Approximate the median age for each distribution.
(408
[59 £ wchin age £25
melian oge AZ Z2T yrs
2000
ay 2 wcdan gee ee
 
we age BE yesSample 1 (cont.)
(b) Approximate the interquartile range for each distribution.
1100 teoo
= 2s ee wes
16 2x2 53 Evshe s
wu ex £ 34
3q-\e Zaye) ws) sxe: Faye)" **
——— >
mca)
velue S
(©). Using the results from parts (a) and (b), write a sentence or two for a history textbook comparing
the age distributions for the years 1900 and 2000.
At the turn of te conta, in (400, *he
og of pecrt= was wach lower then if all b.
qhen we Wit te year 2000. Tn laoo
ieee medion age wae aly 22 3. 2b yous old Ale
2000 ik will be about 36- Rope
now, The widdle SOT SF pope
ol
in the year
oe Laving leage:
w 0D vere ekueen Wed 39 91
whe $.2000 the midlle so% Ul
be between 18 omk 59 genre old,
 
 
Commentary:
‘The medians and interquartile ranges are clearly specified for both the 1900 and 2000 data. The student
describes the shift toward an older population in 2000 by stating how the median increases and how the spread
af the middle 50% also increases. Score = 4
59Sample 2
(a) Approximate the median age for each distribution.
The median age te eth dite baben ald gop of he ge whore th
Oh “tpl toa wat oA a below foe! 7) Ae cad (Wl we
Ye J cdo grt Chie 6 ib ys. th ape, wh S194 the papulldben,
a1 Gn as tabobahrs he aggre kes
eae Gn Ag tbe hh Hots tabblo spo m
eds bly pboe Byes, ci Ul At fe Pople A «7 kl
4g FIs
(b) Approximate the interquartile range for each distribution.
Th vbeywer dl pipe 6 9 pital b te ee eg sue Oe a
tle HW wck pypiftin ds Ghibey. Th? Cap fad by shba
dh hg (gp tgget) bo haw Fhe igpar)
26 %> ]dyr™ 5
eafeaed  W- oe ed- te =. Pos - ays * Bhs:
Son: \ yw: ope Bo He SS yr - Wyre PG
"0
Th apr’. "08 de 200 Ub yn, whl ber SOQ I 3 yn,
(©) Using the results from parts (a) and (b), write.a sentence or-two for a history textbook comparing
the age distributions for the years 1900 and 2000.
4h te yee Gite popilot, ox o while apt be thle, flit
bas Z te Yor "Glan ee ia
+K, ‘pin ig vill thy 4 to Abitord as 73 cemecitate
bw? ibs, /» 100 MO), Nhe Ge P Me igs att be
po Puce wally the A Ae ply YZ,
Commentary:
‘The thinking of this student is clearly stared in words; the reasoning on both the medians and the interquartile
ranges is correct. The conclusion concisely states how both the center and spread of the ages increase between
1900 and 2000. Score = 4
60Sample 3
(@) Approximate the median age for each distribution.
The median as® for the population of
1400 lies betwee! the ages of IS and
GS, whee 50% of the apulatiot rs
abeuc a& below the median. This age is
contained 1A (8,8), roughly 23.
The niredian age €or the G.Goo (ep «leben
ies betweer ~+he ages of
BE and 45, rownly ~ 37.
(>) Approximate the interquartile range for each distribution.
The TAR is Q,7@;), For 'f00, a, 37 and
Q, X10. There fore , the FAR eR? years
er O00, Q,% 63 and Q,* 17.
There fre, the DQR % 36 years
(© Using the results fromm parts (a) and (b), write a sentence or two for a history textbook comparing
the age distributions for the years 1900 and 2000.
During The year 1900, the majority
of the U.S. gopubtion ranged Com
the eases of [0 237, whrle 14
the year Boece, the populate]
ranged Lreni (7 te 53 yrers of,
En gerere| fhe age of the “averse ~
Ee ic hee eee ee
Fre MaSically,
Commentary:
Correct reasoning and good approximations are provided for both che medians and the interquartile ranges,
Although the conclusion states that ages are increasing, the use of interquartile ranges to express this idea is a bit
confused. Both the “majority” and “population ranged” terms-are not quite correct. Score = 3.
aisQuestion 2 Scoring Guidelines
 
4 Complete Response
Shows four blocks of two tanks each, with the pairs of
tanks being in nearly identical conditions with regard to
temperature. The blocks are (1,4), (2.3), (5,8), and (6,7).
Scates cleaely chat this isthe potentially most effective
arrangement of blocks since these paits should be the
most homogencous.
Explains a correct method for randomly assigning
treatments to blocks.
3 Substantial Response
Shows ewo blocks of four tanks each which take into
account the north-south temperature gradient. The
blocks are (1,2,3,4) and (5,6,7,8).
Or, shows four blocks of two tanks each which take into
account the north-south temperature gradient. These
blocks are (1,2), (3,4), (5,6), and (7.8).
Os shows a correct design for the case in which both
foods could be used in each tank.
Sample 1
Explains a method of randomly assigning the wo
treatments to tanks that shows some understanding
of randomization.
2 Developing Response
‘Shows a design that correctly takes temperature into
account, but ignores the randomization,
Or, explains a method of randomly assigning the wo
treatments to tanks and indicates that cemperacure is
o be taken into account in the analysis,
1 Minimal Response
Shows some knowledge of what is meant by blocks, but
is not cleat on any sationale for choosing blocks or any
method of assigning treatments.
(Or, states chat che ewo treatments must be randomly
assigned co tanks but ignores the temperature gradient
 
2. A new type of fish food has become availabie for salmon raised on fish farms. Your task is to design
an experiment to compare the weight gain of salmon raised over a six-month period on the new and the
ld types of food. The salmon you will use for this experiment have already been randomly placed in
eight large tanks in a room that has a considerable temperature gradient. Specifically, tanks on the
north side of the room tend to be much colder than those on the south side. The arrangement of tanks
is shown on the diagram below.
Window pote
   
‘Window
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
62Sample 1 (cont.)
Describe a design for this experiment that takes account of the temperature gradient.
Because of te coon’d symmetry, Vk is) possible te
meteh each tenk with another thet should have
very semiler, Fonot egusl temperatures, The matchings
ore 4 2,3 3, ¥ and ©, F, From each
peir, choose one teak te be fed cite the new ford
and one Henk te be fed orth He old feod, This choice
sheald be dene rendomly Gussibly by the tas of « coin),
AL both the
heginniny ant end of the sie week period,
find
meen weight of He Fish an each type of food,
Then caleulate dre difference dm weight
gh gee end dehemire
3
wid is orgn ificanh
Commentary:
‘The idea of pairing similar tanks to form homogeneous blocks is clearly stated, as is the notion of randomly
assigning treatments to the tanks within a block. It is not necessary 10 discuss the analysis ofthe resulting data
jn any detail. Score = 4Sample 2
 
2. A new type of fish food has become available for salmon raised on fish farms. Your task is to design
an experiment to compare the weight gain of salmon raised over a six-month period on the new and the
old types of food. The salmon you will use for this experiment have already been randomly placed in
eight large tanks in a room that has a considerable temperature gradient. Specifically, tanks on the
north side of the room tend to be much colder than those on the south side. The arrangement of tanks
is shown on the diagram below.
‘Window poe Window
   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Describe a design for this experiment that takes account of the temperature gradient.
To account Sor the temp, gradient, He salmon
Should be divided into He Blowing groups:
in the
1rd : i, weeld be
Bach Cish in these ‘P
eae relatively Sane temp. environ erth aS +
t+7 Ofer fish In tHe gp) lased on room
locaton,
ald New rendomly{assign | Fish in eee
gine the new foc, es gis re other Frok He ad
fay. phter 6 months, compare te weight 92’
oF cach Sisk In cach group. Pry aay auger ae)
in the weigh * gein weeld pare +o feo " .
Yo tae news Sood, since femperotare Ci tas i
have peen neutralized,
Commentary:
In this response, the block arrangement for tanks is chosen correctly and randomization is used properly.
The conclusion is a clear statement on the purpose of blocking and randomization, showing that the student
understands the basic principle. Score = 4
64aL oh We vont Start
arta 9
Sample 3
rp
‘A new type of fish food has become available for salmon raised on fish farms. Your task is to design
‘an experiment to compare the weight gain of salmon raised over a six-month period on the new and the
old types of food. The salmon you will use for this experiment have already been randomly placed in
ight large tanks in a room that has a considerable temperature gradient. Specifically, tanks on the
north side of the room tend to be much colder than those on the south side. The arrangement of tanks
is shown on the diagram below.
‘Window Door Window
North
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Describe a design for this experiment that takes account of the temperature gradient.
The room wourtd we dividé WhO tpo Decits. Tay Wlock
youd VE ob tants 1,2,3,and4 on Ye morn sidt Qf The + oo"
Tr otter wowd WR ahtwiks 56,2 andl Mw s
volt TONS tanh 4,  Pr
where p, denotes the proportion of voters favoring che
new candidate before the incident and p, denotes che
proportion of voters favoring the new candidate after
the incident.
4 223 4 _317
= 2232537, ==
Pe 415 P30
Both samples are large enough that the normal
distribution approximation is appropriace.
Hy: Py = Py
503
537-503
ss bof SOT 8.
Ba- BE my POI SINGS Gq)
2 = 1.08, approximately.
prvalue = 1 ~.8599 = .14
While the proportion of voters in the sample
supporting the candidate after the unfortunate remarks
were maide is less chan the proportion of voters
supporting the candidate before the remarks were made,
the difference is not significant and can reasonably be
antibuted to chance,
aeSample 1
4. A random sample of 415 potential voters was interviewed before the start of a state-wide
campaign fr poveraor 223 of te 415 sid hey fred the ew candidate oer ie incumbent
ade several unfortunate remarks.
the election. Subse-
eth neermic sample of 630 potential voters Showed that 317 vers favored the nw cand
Do these data support the conclusion that there was a decrease in voter support for the new candidate
after the unfortunate remarks were made? Give appropriate statistical evidence to support your answer.
LMeckion, Birce O shave use Mompde peopeciiory,
Leach chaueation usithin gach Aemple ans
Andupendent 4 amd mip 41 (I-p,), Naps axel
ra (i-ba) ante ado geeahae than or 2gua-l
to ) Burd yaa o too propsction
Zee. La found He Ateendaced Qe Rte
He peepentin to be Srp 2 jee , Pall-pe)
2 OMNSS TAB aunerthe Da ae
and Aan beneguad ee , Hoag
Compu fhe GRiticot z-velue
peat a which, thule /:08/7,Sample 1 (cont.)
The p : ty Hat 2 ta ysalie than
/. ott 4a +139. There he mat Undigh.
Mgrupiccnt aviderce to eh
ot He 5, D8 The mou Candida
chum, Rornasebo did ey
Commentary:
The student writes out in great detail exactly what the reasoning process is. The reasoning is very clear and easy
to follow. Ir cavers the nature of the problem, the assumptions, the mechanics of the test, and the conclusion,
which is stared in the context of the problem, Score = 4
72Sample 2
4. A random sample of 415 potential voters was interviewed 3 weeks before the start of a state-wide
campaign for governor; 223 of the 415 said they favored the new candidate over the incumbest.
However, the new candidate made several unfortunate remarks one week before the election, Subse-
quently, a new random sample of 630 potential voters showed that 317 voters favored the new candi-
due N=4IS X= aad Ng=G3Ro %473\4
Do these data support the conclusion that there was a decrease in voter support for the new candidate
afer the unfortunate Fermarks were made? Give appropriate statistical evidence to support your answer.
yer POV
Hot Piz Py WR Gees Berne eh
Pa Proportion of vorer Spot
3
 
Hat py? Pa \ Week be fore be ction
Q praparhon Z +St +
Z= 1.083
prval= .\397F
 
Canclosion + do not reyect X2= 2F
Ho because p-al= 1ST Aas Gag
\oefere
(S rot Stanshcall Pas .sosa) clearer
SIQME Cantar fe «10 5
a >
USiile there 1S some. S-
eviderce Gost Boy Taser
tree is Wa aA
evidence tO crc sect to See ted 1
fro there. was adecrase SLR Gas a pe
WANGer SUpport far He Zz est t
Ness candidote ater 7
tne Unforrumde Yermarrs, NPL? S PABC-SHD=
wer vrowe |
s 2A2-FBs
WCrpyI7S =
ASC -4.69D= 194,085
Pars > 620CSoAD=
317F.GarS
MO p75 > Asa975
mest likely tno State
nos 7 1 x SORNAE
Site
Commentary:
The response cleatly covers the type of rest being done. the assumptions (with a small ertor in notation), the rest
statistic and p-value, and the correct conclusion. The conclusion provides a statement in the context of the
problem. Score = 4Sample 3
4, & random sample of 415 potential voters was interviewed 3 weeks before the start of a state-wide
‘campaign for governor, 223 of the 415 said they favored the new candidate over the incumbent.
However, the new candidate made several unfortunate remarks one week before the election. Subse-
quently, a new random sample of 630 potential voters showed that 317 voters favored the new candi-
date.
Do these data support the conclusion that there was a decrease in votet support for the new candidate
after the unfortunate remarks were made? Give appropriate statistical evidence to support your answer.
Hier Trete wes 92- change in vetee be?
Suppers qedecmset after te remarks
Wa There was a decrease in velee Pap>o
soppeer after the ‘remarks a
=O
te SR7y cae fhe 608%" Ge
at-Py + Pal Pa)
Wy ey
Zz:
      
\,O7
P= 1422 Ke Of
Based on Flack Lk sutiicrenr evidence, fa i
fe eject Be the there? was no change in voter
Soppork s%tae jhe remarks the new - candidate nade.
Commentary:
‘The student carries out the correct test and makes a proper conclusion, bus some of the symbols are not defined
and no mention is made of assumptions. Score = 3Question 5 Scoring Guidelines
 
4 Complete Response
A. Selects an appropriate test of significance.
Observes that data are paired by hour of day and
indicates a paired t-test is appropriate OR observes
that the data are paired by hour of day and justifies
choosing a two-sample t-test (or confidence interval
for the difference of two proportions) OR worries
about assumptions for a t-test and so chooses a
sign test OR performs a substantial data analysis.
 
B, States and addresses assumptions necessary for t-test.
‘The dot plot below shows no evidence that the
differences aren't normally distributed.
 
   
  
25 50 75
(For 2 ewo-sample t-test, mentions thac outliers
indicate a potential problem.)
C. Carries out a test of significance.
States the hypotheses correctly, with two-sided
alternative, defining any nonstandard symbols.
Hy? ny = Byrn, = 0
Hin, # worm, #0
Calculates an appropriate test statistic, possibly
‘with trivial arithmetic error.
d-0_ il
pene
Sifq | 428/09
 
=078
(Por ewo-sample t-test, t = 0.519 and p = 0.61,
pooled or unpooled. For a sign test, +-+-++-0+ s0
P= 0.727.)
Correctly approximates the P-value from a table or
calculator.
Wich 8 degrees of freedom, the two-sided P-value is
0.46 (OR compares t= 0.78 with critical value of
2.306).
 
 
OR constructs and interprets a 95% confidence
interval for the mean difference:
   
14(2. 316( 438)
  
113.29 or(-2.18,4.40)
a
OR a 95% confidence interval for the differ-
ence of two means: (-3.47, 5.69)
D. Correctly states a conclusion in the context of the
situation.
‘The difference in the mean percentages in the samples
of defective chips produced by ovens A and B isnt
statistically significant. [there was no difference in
the percentages, a mean absolute difference of 1.1] or
greater would happen 46% of the time with random
samples of size 9.
Os for the confidence interval: Since the confi-
dence interval includes zero, there is no evidence
that one oven differs from the other in terms of
mean percentage of defective chips
3 Substantial Response
Performs a test of significance but
Doesn't mention the assumptions for the rest used.
OR
States an incorrect conclusion
OR
Males ewo or theee less significant omissions or errors
in the test of significance, such as
doesn't make it clear by words or formula which
test they are using
chooses a ewo-sample eestor a sign test without
considering che paired terest
fails co lise hypotheses
does a one-tailed test or forgets to double the P-value
‘says must use a t-test because n is small
uses 2-test, nor Cxest
mentions normality assumption but doesnt check ie
graphically or appeal co robustness
confuses parameters and statistics
1 docsnit define nonstandard symbolsQuestion 5 Scoring Guidelines (cont.)
 
1 Minimal Response
 
forgets “77 in formula fore Recognizes thar the problem involves an inferential
statistical argument
1 uses wrong critical value or degrees of freedom
Does little more than carry out the mechanics of a test
15 “acces” he nll hypothesis or uses similar caress ra cuch as those done by a caleulaton
language in conclusion
gives correct, but minimal, conclusion (“do not ‘Note: Since we are using holistic grading, a deficiency
reject H,”) or a generic conclusion that doesn't in one part can be compensated for by outstanding
relate to the ovens work in another.
2 Developing Response
 
Performs test of significance except makes both major
errors OR an equivalenc combination of errors.
Sample 1
5S. A company bakes computer chips in two ovens, oven A and oven B. The chips are randomly assigned
to an oven and hundreds of chips are baked each hour. The percentage of defective chips coming from
these ovens for each hour of production throughout a day is shown below.
 
Percentage of Defective Chips
 
 
Hour | Oven A Oven B
1 45 36
2 32 37
3 34 33
4 31 34
$ 35 33
6 37 32
7 31 33
8g 30 30
2 27 24
 
 
 
 
“The percentage of defective chips produced each hour by oven A has a mean of 33.56 and a standard
deviation of 5.20. The percentage of defective chips produced each hour by oven B has a mean of
32.44 and a standard deviation of 3.78. The hourly differences in percentages for oven A minus oven B
have a mean of 1.1] and a standard deviation of 4.28.
Does there appear to be a difference between oven A and oven B with respect to the mean percentages
of defective chips produced? Give appropriate statistical evidence to eae pov
etn.
Te test for, a dMerence cen oven d
cel mote am an 2 ena we 7 gee
des: awl be esol The reasen *s a .
beaLler phe LZ shows a deed peshre
a4 soci Lon bedwren the Percentage
of defleckive chips. The prota bittySample 1 (cont.)
of obfaing such a Ag A Nneavity is b-hoves
Reording to @ Minene Fegression Hot TH
ae ndente < wists, a tee saeple ttesl
fanned, bs, fen 4 Lee
= pemsin ef 6d This, the nlf hyper bases
7 lV EL ices of fhe peceeol, debe Or
'PS Vs . The olfecna hey, L . not
thod He tnean bhacorce  YOUPhes 73)
CO. A thendard aloha oh. 62 6D Goel,
 
The general €¢ ution fs a one gample £
yest upon the diklerence ov 4 4a
Vr
The degrees of Kee Jam (sea ce
Subshhting 4s SE or Hz 7790
The pre bab, SrA of of oblarnrng
guch a telatHishe ef 2 pile. 776 Oarce
O deg.ees oh freedom ys , USER Thrs
peebaby (ty value 13 greats Phan ak he
The wyll/ hyae thesis ) 7? / tferen ce eels
between vm 4 pnd Oren @ for the
poeportion of defective tee. must be
acces ec.
Commentary:
‘The response provides a detailed explanation of why the data are regarded as paired (although the regression
part is not essential) and even plots the data. The paired t-test is carried out and a correct conclusion is stated in
terms of a comparison between the ewo ovens. (It would be good to plot the differences to show that there are
no outliers.) Score = 4
77Sample 2
 
5. A company bakes computer chips in two ovens, oven A and oven B. The chips are randomly assigned
to an oven and hundreds of chips are baked each hour. The percentage of defective chips coming from
these ovens for each hour of production throughout a day is shown below.
Percentage of Defective Chips
 
 
 
Hour | Oven A Oven B
1 45 36
2 32 37
3 34 33
4 3h 34
5 35 33
6 37 32
7 31 33
8 30 30
9 27 24
 
 
‘The percentage of defective chips produced each hour by oven A has a mean of 33.56 and a standard
deviation of 5.20. The percentage of defective chips produced each hour by oven B has a mean of
32.44 and a standard deviation of 3.78. The hourly differences in percentages for oven A minus oven B
have a mean of 1.11 and a standard deviation of 4.28,
Does there appear to be a difference between oven A and oven B with respect to the mean percentages
of defective chips produced? Give appropriate statistical evidence to support your answer.
_ Te dota is given tous in matched
Paits form, protche hoor. “To analyze
Mathes pairs data TAwill use a one ~Somple
Attest On The dickerees Lge bis to
Aqwount Sor the non - indapadere thet matched
ers has.
He MeO Hy MieetO
Kyac> AM THe — WNHO _ 77g
S4OF Fe TEI Wg
n=q Tin TE
AS (05
de=g
 
 
72Sample 2 (cont.)
 
crital tye gg 2308
3, 3067.7 76
Beause the wit Ff less. then “
++ statistic L connet rejeet Ho infqvor oF Me.
That ne evidee to sa est vu dittereny in
the percentage oF bared ates Ve av in the oven,
“Commentary:
‘The student correctly recognizes this as a matched pairs problem and analyzes the data accordingly. “The
conclusion is correctly stared in context. Although assumptions are nor mentioned, the student did look ac che
differences, as indicated by the numbers added to the chart. Score = 4
[79Sample 3
 
. A company bakes computer chips in two ovens, oven A and oven B. The chips are randomly assigned
to an oven and hundreds of chips are baked each hour. The percentage of defective chips coming from
these ovens for each hour of production throughout a day is shown below.
 
 
Percentage of Defective Chips
Hour | Oven A Oven B
1 45 36
2 32 37
3 34 33
4 31 34
5 35 33
6 37 32
7 31 33
8 30 30
9 27 24
 
 
 
 
“The percentage of defective chips produced each hour by oven A has a mean of 33.56 and a standard
deviation of 5.20. The percentage of defective chips produced each hour by oven B has a mean of
32.44 and a standard deviation of 3.78. The hourly differences in percentages for oven A minus oven B
hhave a mean of 1.11 and a standard deviation of 4.28.
Does there appear to be a difference between oven A and oven B with respect to the mean percentages
of defective chips produced? Give appropriate statistical evidence to support your answer.
See student response on facing page.
80Sample 3 (cont.)
an 748 Ae pucenTge.  depsBiuze Chipt« gor
‘Aa A4p Abc preening 2 obpetnie Chips gor
Ae Hib -32-44
ae
q %
Bb 2.0092 & CohusLick fom 7) -B2
2 6090S (from T1-B2. wth, df ly
Aces Car om OD neat
hers. ae ut smog iviglnce to iycet He Aw
favor Of Hoe rar for Bins 20 n0
klwen the prcentagt @ chyecliir chip
bitin evens A aref &
Rash. cto even Ate akowek cht ad
wie Ang Laas Hm 16 Lt my aptect
Ep Sereee en ae eae arr rae % Anyis sorte tek ae
Commentary:
Here, the data are analyzed by a two-sample t-test on the difference between two means. Given the assumption
‘of two independent samples, the analysis and conclusion are correct. The student correctly notes that there is
some skewness in the data. Score = 3
81Question 6 (Investigative Task) Scoring Guidelines
 
4 Complete Response
L
I.
ML
NV.
Correctly estimates the asking price in dollars for at
least ewo of the three models, including back
transforming the predicted value for at least one of
models b oF c.
a. Price = -58.1 + 0.719(88) = 5.172
asking price is $5,172
b. Ln(price} = -14.9 + 0.185(88) =
exp(1.38) = 39749
asking price = $3,975
c. Sqri(price) = -13.3 + 0.176(88) = 2.188
(2.188)? = 4.7873
asking price = $4,787
 
 
380
 
Describes the major shortcoming to be the non-
linear pattern in the seatterploc oF residual plot for
all three models.
Suggests a new model that successully deals with
the non-linearity of the data. The prime contenders
for this model are:
 
Fica simple linear model after the first two or three
years are dropped.
(2 =.978 with liccle pattern in the residuals after
dropping 79, 82 and $4.)
Fit separate linear models to the earlier andl later
years
(R? = .985 for the years 86 to 93, with little pattern
in the residuals.)
 
Fica model that attempts to model the curvature in
the data, For example, fita quadratic model to all of
the dacs
(R? = 974 with litle pattern in the residuals for a
quadratic model.)
 
Justifies why this model is bettes. For example,
comments that there is no pattern in the residuals
as seen from looking at the fitted model on the
scatterplot or from looking at the residual plot.
ae
3 Substantial Response
Fails to do one of the following satisfactorily:
Pare (for example, by filing to back transform
the prediction)
describe the major shortcomings of the three
models
1 justify why the new model is better (for example,
by failing to comment on the residual plor)
2 Developing Response
 
Fails to do one of the following satisfactorily:
Pare I and describe the major shortcomings of the
three models
Parc and justify why the new model is better
suggest a new model and justify ic
describe the major shortcomings of the three
models and justify why the new model is better.
1 Minimal Response
Gives correct responses to one of the items I, Il, of HL
above. Note: Students cannot get IV correct without
first specifying a new model.Sample 1
 
(@) Use Model 1 to establish an asking price for your 1988 automobile.
Price = 58.1 40.119 (88) = [e5.s70\
(b) Use Model 2 to establish an asking price for your 1988 automobile.
Qu Price = —14.9 + 0.185 (88) = 1.38
vier = @' FF 2153, 970
(©) Use Model 3 to establish an asking price for your 1988 automobile.
SPriea = 13.3 + OAT (8B) = 2.198
Crier = 2.188% ~)94, 790Sample 1 (cont.)
(@) Describe any shortcomings you se in these tzee models
Aitleagh the couvelation coefficients ave af
quite large, tle veridual glob alk show
a dinkined potun, wliclh wear that
witlen Gt is tle covet one fev tle date
(©) Use some or all of the given data to find a better method for establishing an asking price for your
1988 automobile. Explain why your method is better.
Fvow te plet Neodel 4 ck do fear tut
a bctln fit for te Anta vtertdh Cy. tro Lies
iuokead of ace. the fivet cue woutd be the
beast-aquerer veqvecsion Line on te yearo
prioy ke 1966 and would Ge valid fer
there yeave, WEL the otter exe wold &
the vequersion Live on tle > of 1986 and
bakes, ond would Ke oatid CO yenvo
Fa thin case, amy pativn in the veridual plot
vot dian ppeaw, and the aabing prsee of the
4933 arbousi con be dled fren the
weeond Live of ae Ke.
oar od tine
Ant Live
Commentary:
Parts (a), (b), and (c) show correct calculations and (d) contains a comment on the patretn in the residual plots.
Pare (@) contains a clear description of how the data could be split into two groups, each showing a linear trend
boc with different slopes. Score = 4
[84 |Sample 2
(a) Use Model 1 to establish an asking price for your 1988 automobile.
erites ~ SEV NA yen?
= -5B.) + 1WV4- $4
2 TATL Ghovsand dollere)
c- Price Frain)
(b) Use Model 2 to establish an asking price for your 1988 automobile.
he price - (44 + NBS-yeor
= “HAF 185-88
bp 7 |.o%
pee s BATT Hoveond 8)
fe prigee 429795
(©) Use Model 3 to establish an asking price for your 1988 automobile.
peice = 713.3 + bear
= -\3,3 ¥ N16 8S
= V.\ 84
perce 2? \get= 4.197 (thovsand 3)
proce 84197)
85Sample 2 (cont.)
(© Describe any shortcomings you see in these three models.
The veoduals, which should be voubow in the
eck reqvesson, exhibi} curved acters
ee avaphs- Aloo, #%, which ehovdd
ve ok least 81 ov 4, 31 446
ow every qeephe
or lower
( price Vs. Ds year does nok correct Ahig.
° ugeedtinersene fing a beer method fr exalising an asking pc fr your
Eliminate Lrom our dghe pool all cars
ore thaw three years away from ovr
\V@F car® before \VWES or offer oe
Ahen, We get a doka set wth the following
araph (oketehed Svom colevleter):
and 0 least eq veces Fey Vession
erie| . of Cprice + -82 = Lone Geer).
- yeow
The plot gt the rodvals te Bo
<
 
which gs Leirly mundom-
year
Subshirvting tn oer year, we getia prec
of prices - 42+ [,0%6ls9) = 444g = BUG
which — Seems correspond to
neorby years Laicly well
Commentary:
“The numerical calculations in the first three parts are correct. The pattern in the residuals is recognized, The
solution to improve the fit is to concentrate on the years around 1988, and this is reasonable way co improve
the fit. Score = 4
 
86Sample 3
 
(a) Use Model 1 to establish an asking price for your 1988 automobile.
$(88)= FATD these dellers
BANTD tres’ os
-s%,1 10, 79+ 8
() Use Model 2 to establish an asking price for your 1988 automobile.
= 1,38 af
wool Pe 5 a 709 Heard dlees
14.9 + 0.18538 =
(©) Use Model 3 to establish an asking price for your 1988 automobile.
2
“13.34 O.176- BE= BIBT 2,188 = 4787S theserd dillersSample 3 (cont.)
(@) Describe any shortcomings you see in these three models.
These models inchde all of the deta, According fo fhe regression egeshon
for the First mudel, 0 1980 cor vould sell for -O.SE Howard dollars, We know
, You can self almost ary
that cors will sell for a minimum amouat of mo
coe Gor about a thevsaad dellacs, You shevid there not include data fom cars
older than a certain yes
(©) Use some or all of the given data to find a better method for establishing an asking price for your
1988 automobile. Explain why your method is better.
T+ oppenrs that the regression equation for this date woull Fit
beter if the date From years (977 and 198) were omitted. Thue
were to Find out prices for cors older than 1784 we would probably
Sind that most of them sold for grand J fheaand dollars, by ontHing
~ Gor mete! L
"Dt ad Gh oor new Cepression egetionis ~BII34A+ O.974 7-year,
7
£82 97,1R% This is & much beter Fit thaa the previous eg ration,
Our new asking price would be 4, 64 thousand dellovs which would be
Closer 4 the true market valve,
Commentary:
‘The calculations in (a), (b), and (6) are correct, In part (e), a good solution is suggested in terms of eliminating
the early years from the analysis. The main weakness of the response is that the pattern in the residuals is not
 
recognized in (d). Score = 3
88 |Ga Statistical Information
Table 4.1 — Section II Scores College Comparability Studies
| How AP Grades are Determined Reminders for all Grade Repore
@ Table 4.3 — Grade Distributions Recipiencs
Table 4.4 — Section I Scores and & Reporting AP Grades
AP Grades Purpose of AP Grades
Table 4.1 —Section II Scores
“These ate the score distribucions for the total group of candidates,
on cach frce-response question from the 1997 exam.
 
  
 
Pe Cm Ce
Numberof At | Numberof — % At | Number of % At
Score Students Score | Students Score | Students Score
5H 7 ist is 948 124
3 1261 165 124 16.1 179 23
a 2 iia or 4675 od i410: 185
1 1612 2b 885 ne 969 7
a 2797 366 530 69 3551 464
*NR 200 26 188 25 59 24.
Cr Ca
Number of Numberof — % At [Numberof — % At
Score Students Students Score | Students Score
Se 170 22
7 157 21
6 2a Br
5 292 38
a 159, 2 19 02 580 26
3 2629 344 1285 169 594 78
2 oo ie | ae 330) 1841 261
1 1128 148 1626 212 734 36
a0 2168 283 isis ie 2570 336
NR 148 19 38 45 467 6
“NR — No response. Suident gave either no response ora response not on the
 
“Question 6 was read by wo different Faculty consultants and the ro scores were combiny
 
 
Toual Candidaces role 7,686 1046 7.646
Mean 1.89 1.06 139 uaa
Standued Deviation 0.84 139, 1.08, 2.05
Mean as % of 33 7 35 2
  
Maximum SeoteHow AP Grades are Determined
AD Statistics students can receive 0 to 50 points in each
section of the exam. However, these scores are not
released to the student, school, or college. Instead, these
raw scores are converted to grades on an AP 5-point
scale, and it is these grades that are reported. This
conversion involves a number of steps:
1. The multiple-choice score is calculated. To adjust
for random guessing, a fraction of the number of
‘wrong answers is subtracted from the number of
right answers. This fraction is 1/4 for five-choice
questions (as on the Statistics exam), so that the
expected score from random guessing will be zero.
2. The free-response score is calculated. When the
face-response section includes two or more parts,
those parts are weighted according to the value
assigned to them by the Development Committee.
This allows the Development Commitee co place
more importance on certain skills to correspond
to their emphasis in the corresponding college
curriculum.
3. Acomposite score is calculated. Weighting also
comes into play when looking at the multiple-
choice section in comparison to the free-response
section. In consultation with experts from the
College Board and ETS, the Statistics committee
decided that each section should contribute an
equal amount to the total score. The maximum.
composite score was 100, with each section
1g up to 50 points. The Scoring
‘Worksheet on the facing page details the process
of converting section scores to composite scores
for this examination.
contrib
 
—s
4, AP grades are calculated. The Chief Faculty
‘Consultant sets the four cut points that divide the
composite scores into groups. A variety of informa-
tion is available to help the CEC determine the
score ranges into which the exam grades should fall:
1 Discributions of scares on each portion of the
multiple-choice and free-response sections of,
the exam are provided, along with totals for
cach section and the composite score otal.
With these tables and special statistical tables
presenting grade distributions from previous
years, the CEC can compare the exam at hand
to results of other years
For each composite score, a cable summarizes
student performance on all sections of the exam.
| Finally, on the basis of professional judgment
regarding the quality of performance
represented by the achieved scores, the CEC
decermines the candidates’ final AP grades.
See Table 4.3 for the 1997 AP Statistics Exam
grade distributions.
 
If you'te interested in more detailed information about
this process, please see the “Technical Cornet” of our
website: www.collegeboard.org/ap. There youl also find
information about how che AP exams are developed,
how validity and reliability studies are conducted, and
other nuts-and-boles data on all AP subjectsTable 4.2 — Scoring Worksheet
 
 
 
 
 
 
A x y)* 142865 0
Number correct Number wrong Multiple-Choice Weighted
(out of 35) Score Section I
m (Round to Score
nearest whole 5
umber Iles than .
zee, enter 2670.) fT
Seite Mee Wal i srsaetss :
Question 1 x 1.875 = S :
Tout ora Do netroundh =
Question 2 X 1.875 =_ ae .
(outar ay {Do not rounah .
uestion 3 x 1.875 = 7
a (oat oray 9 ean _
estion 4 x 1875 = : |
a (out oray > eee A |
. |
uestion 5 x 1.875 = 2 }
See 75 - en . |
Question 6 x 1,562 eto
 
Tout oF
Sum =
‘Wonstrounay
Weighted
Section II
(Oo not round.)
   
(eeiniseicesrscia’
 
‘Weighted Weighted ~~ Composite Score
s Section IT (Round to the nearest
‘Score ‘whole number)
 
Score
    
  
    
   
 
 
AP Grade
Composite
Score Range*
68-100
54-67
41-53
29-40
0-28
=Nnona
“The candidates’ scores are weighted
according to formulas determined in advance
‘2ach year by the Development Committee
to yield raw composite scores: the Chief
Faculty Consultant is responsible for
‘converting composite scares to the 5-point
AP scale.Table 4.3 — Grade Distributions
More than 62% of che candidates earned an AP grade of 3 or higher.
   
 
Extremely well qualified
Well qualified 4
Qualified 3
Possibly qualified 2
No recommendation 1
Total Number of Students 7.646
Mean Grade 2.97
Standard Deviation 1,33
Table 4.4 — Section | Scores and AP Grades
This table gives che probabilities that a student would receive a particular grade on the 1997 AP Statistics Exam
given that studer
 
’s score on the multiple-choice section.
 
fod Cre
 
30.10 35, 0.0% 0.0% 0.6% 19.6% PB 13.7%
  
 
25 t0.29. 0.0% 0.4% 19.4% 60.8% 193% 23.7%
211024 0.0% 122% oka 03% 20.1%
15 t0 20 10.2% 60.3% 28.1% 0.0% : 24.1%
Ow 14 85.4% 14.0% 0.6% oo oe ee
Toral 18.1% 196% 245% 221% 15.6% 100.0%
92 |Studies
 
College Comparab
Because the 1997 exam was the first one developed for
statistics, a comparability study was done. In this study,
 
college students enrolled in introductory statistics
courses equivalent to the AP Statistics course were given
amini-version of the exam. These mini-versions
contained a subset of the questions in the exam, The
scores obtained by the college students and the grades
they received in their course were used to help deter-
mine the appropriate AP grade for the AP students
taking the examination,
The AP Program has conducted college grade
comparability studies in all other AP subjects as well
As with Statistics, these studies compared the perfor-
‘mance of AP Exam candidates with that of college
students in related courses who have taken the AP Exam.
sa the end of their course. In general, AP cuspoints are
selected so that the lowest AP 5 is equivalent to the
average A student in college, the lowest AP 4 equivalent
to the average B student, and the lowest AP 3 equivalent
to the average C student (see figure below).
ee
eee
5
A
4
B
3
c
2
D
1
‘To ensiue comparability of grades from year to year
and to maintain a certain level of difficulty, some
multiple-choice questions from previous AP Scatistics
exams will be included on each new examination,
Reminders for All Grade Report
Recipients
AP Examinations are designed to provide accurate
assessments of achievement. However, any examination
has limitations, especially when used for purposes
other than those intended. Presented here are some
suggestions for teachers to aid in the use and
interpretation of AP grades.
AP Examinations are developed and evaluated
independently of each other. They are linked only
by common purpose, format, and method of
reporting results. Therefore, comparisons should
not be made between grades on differenc AP
Examinations. An AP grade in one subject may not
have the same meaning as the same AP grade in
another subject, just as national and college
standards vary from one discipline to another.
AP grades are not exactly comparable to college
course geades. However, the AP Program conducts
research studies every few years in cach AP subject
to ensure that the AP grading standards are compa-
rable to those used in colleges with similar courses
| The confidentiality of candidace grade reports
should be recognized and maintained. All individu-
als who have access to AP grades should be aware of
the confidential nacure of the grades and agree to
maineain their security. In addition, school districts
and states should not release data about high school
performance without the school's permission.
@ AP Examinations are not designed as instruments
for teacher or school evaluation. A large number
of factors influence AP Exam performance in a
particular course or school in any given year. As a
result, differences in AP Exam performance should
be carefully studied before being actributed co the
teacher or school.
Where evaluation of AP students, ceachers, or
courses is desired, local evaluation models should be
developed. An important aspect of any evaluation
model is the use of an appropriate method of
comparison or frame of reference to account for
yearly changes in student composition and ability,
as well as local differences in resources, educational
‘methods, and socioeconomic factors.
93|The “Report to AP Teachers” can be a useful
diagnostic tool in reviewing course results. This
report identifies areas of strengch and weakness for
each AP course. This information may also help
to guide your students in identifying their own
strengths and weaknesses in preparation for future
study. (See below for information on how to obtain
this report.)
Many factors can influence course results. AP Exam
performance may be due to the degree of agreement
berween your course and the course defined in the
relevant AP Course Description, use of different
instructional methods, differences in emphasis or
preparation on particular parts of the examination,
differences in pre-AP curriculum, or differences in
student background and preparation in comparison
with the national group.
Reporting AP Grades
 
 
‘The results of AP Examinations are disseminated in
several ways to candidates, their secondary schools,
and the colleges they select.
College and candidate grade reports contain 2
cumulative record of all grades earned by the
candidate on AP Exams during the current or
previous years. These reports are sent in early July.
(School grade reports are sent shortly thereafter.)
Gcoup results for AP Examinations are available to
AP teachers whenever five or more candidates at a
school have taken a particular AP Exam. This
“Report to AP Teachers” provides useful informa-
tion comparing local candidate performance with
that of the total group of candidates taking an
exam, as well as details on different subsections
of the exam.
94
Several other reports produced by the AP Program
provide summary information on AP Examinations.
State and National Reports show the distribution of
grades obtained on each AP Exam for all candidates
and for subsets of candidates broken down by sex
and by ethnic group.
The Program also produces a one-page suramary of
AP grade distributions for all exams in a given year.
For information on any of the above, please call AP
Services at (609) 771-7300 or contact them via e-mail
at apexams@ets.org.
Purpose of AP Grades
AP grades are intended to allow part
 
ipacing colleges
and universities to award college credit, advanced
placement, or both to qualified students. In general,
an AP grade of 3 or higher indicates sufficient mastery
of course content to allow placement in the succeeding
college course, or credit for and exemption from a
college course comparable to the AP course. Credit
and placement policies are determined by each college
or university, however, and students should be urged
to contact their colleges directly to ask for specific
Advanced Placement policies in writing.IIL AP Publications and Videos a
‘A number of AP publications and videos are available
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school and college faculty learn more about the AP
Program and its courses and exams. To sort our those
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to the following key:
Students and Parents SP
‘Teachers Ty
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and Administrators A
College Faculty ci
You can order many items online through the
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Publications may be returned within 30 days of
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AP Bulletin for Students and Parents: Free SP
This bulletin provides a general description of the
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‘AP courses. It describes each AP Exam, lists the advan-
tages of taking the exams, describes the grade and award
options available to students, and includes the upcom-
ing exam schedule.
College and University Guide to the AP Program:
$10 CA
This guide is intended to help college and university
faculty and administrators understand the benefits of
having a coherent, equitable AP policy. Topics included
are validity of AP grades; developing and maintaining
scoring standards; ensuring equivalent achievement;
state legislation supporting AP; and quantitative profiles
of AP students by each AP subject.
 
 
The College Handbook with College Explorer”
CD-ROM: $25.95 SRTAC
Includes brief outlines of AP placement and er
policies at ewo- and four-year colleges across the country.
Noves number of freshmen granted placement and/or
credit for AP in the prior yea
 
 
Course Descriptions: $12 SRTAC
Course Descriptions provide an outline of the AP
course content, explain the kinds of skills students are
expected to demonstrate in the corresponding introduc~
tory college-level course, and describe the AP Exam.
‘They also provide sample mulciple-choice questions
with an answer key, as well as sample free-response
questions, A set of Course Descriptions is available for
$100. Not included in this set are Course Descriptions
for Computer Science, Government and Politics, and
Statistics, which are available for downloading from the
AP section of the College Board website (fice of charge)
Five-Year Sct of Free-Response Questions: $5 T.
This is our no-fiills publication. Each booklet contains
copies of al the free-response questions from the last
five exams in its subject; nothing more, nothing less.
Collectively, the questions represent a comprehensive
sampling of the concepts assessed on the exam in recent
years and will give teachers plency of materials to use for
essay-writing or problem-solving practice during the
year (If there have been any content changes to the
exam in the past five years, it will be noted on the cover
of the booklet.)
=Grading, Interpreting, and Using Advanced
Placement Examinations: Free AGT
A booklet containing information on the develop-
ment of scoring scandards, the AP Reading, grade-
setting procedures, and suggestions on how to
interpret AP grades
Guide to the Advanced Placement Program: Free A
Written for both administrators and AP Coordinators,
this guide
provides general information about AP, such as how
to organize an AP program at your high school,
the kind of training and suppore that is available for
AP teachers, and a look at che AP Exams and grades.
‘The second section contains more specific details
about testing procedures and policies and is intended
for AP Coordinators.
 
ivided into two sections. The first section
Released Exams: $20 T
About every four yeats, on a staggered schedule, the AP
Program releases a complete copy (multiple-choice and
free-response sections) of each exam, as in the case of
the 1997 Statistics Exam.
Packets of 10 ($30): For each subject with a released
exam, you can purchase a packet of 10 copies of that
year's exams for use in your classroom (e.g,, to simulate
an AP exam administration).
Secondary School Guide to the AP Program:
s10
This guide is a comprehensive consideration of the
AP Program. It cavers topics such as: developing or
expanding an AP programs gaining faculty, adminisera-
tion, and community support; AP grade reports, their
use and interpretation; AP Scholar Awardss receiving
college credie for AP; AP teacher training resources;
descriptions of successful AP programs in nine schools
around che country; and “Voices of Experience,” a
collection of ideas and tips from AP teachers and
administrator.
AT
‘Videoconference Tapes: $15 TC
AP conducts live, interactive videoconferences for various
subjects, enabling AP teachers and students to talk
directly with the Development Committees that design
the AP Exams. Tapes of these events are available in
VHS format and are approximately 90 minutes long.
‘Teacher's Guides: $12 T
‘Whether you're about to teach an AP course for the first
time, or you've done it for years but would like to get
some fresh ideas for your classroom, the Teacher's Guide
can be your mentor. It contains syllabi developed by
high school reachers currencly ceaching the AP course
and college faculty who teach the equivalent course at
their institution. Along with detailed course outlines
and innovative teaching tips, you'll also find extensive
lists of recommended teaching resources.
AP Pathway to Success (video, available
in English and Spanish): $15 SRT, A,C
This 25-minute-long video takes a look at the AP
Program chrough the eyes of people who know AP:
students, parents, teachers, and college admissions staff
‘They answer such questions as “Why Do Ie”, “Who
Teaches AP Courses?”, and “Is AP For You?”. College
students discuss the advantages they gained through
taking AP, such as academic selfconfidence, writing
skills, and course credit. AP teachers explain what the
challenge of teaching AP courses means to them and
their school, and admissions staf explain how they view
students who have stretched themselves by taking AP
Exams. There is also a discussion of the impact that an
AP program has on an entire school and its community,
and a look at resources available to help AP teachers,
such as regional workshops, teacher conferences, and
What's in a Grade? (video): $15 Be
AP Exams are composed of multiple-choice questions
(scored by computer), and free-response questions that
are scored by qualified professors and teachers. This
video presents a behind-the-scenes look at the scoring,
process featuring footage shot on location at che 1992
‘AP Reading at Clemson University and other Reading
sites. Using the AP European History Exam as a basis,
the video documents the scoring process. Ir shows AP
faculty consultants in action as they engage in scholarly
debate to define precise scoring standards, then train
others to recognize and apply chose standards. Footage
of other subjects, interviews with AP faculty consule-
ants, and explanatory graphics round out the video.
[96 |Umi eats e (es)
   
1996-97 Development Committee
 
: Rosemary Roberts, Chair Daniel Teague
. Bowdoin College North Carolina School of
Brunswick, ME ‘Science and Mathematics
Durham, NC
Fred ©. Djang
Choate Rosemary Hall Jessica M. Utts
Wallingford, CT ‘University of California:
Christopher R. Olsen Walter O. Walker
George Washington Eckerd College
High School St. Petersburg, FL
Cedar Rapids, 1A
Ann E. Watkins
Dian C. Resnick California State University:
Bellaire Senior High School Northridge
Houston, TX
Chief Faculty Consultant:
Richard L, Scheaffer
University of Florida
Gainesville
ETS Consultants:
Jeff Haberstroh
“Michael Ponisciak