CHAPTER 1
INTRODUCTION
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Opening Example
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
WHAT IS STATISTICS?
Definition
Statistics is a group of methods used to
collect, analyze, present, and interpret
data and to make decisions.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
TYPES OF STATISTICS
Definition
Descriptive Statistics consists of
methods for organizing, displaying, and
describing data by using tables, graphs,
and summary measures.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Case Study 1-1 Descriptive Statistics
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
TYPES OF STATISTICS
Definition
Inferential Statistics consists of
methods that use sample results to help
make decisions or predictions about a
population.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Case Study 1-2 Inferential Statistics
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
POPULATION VERSUS SAMPLE
Definition
A population consists of all elements
individuals, items, or objects whose
characteristics are being studied. The
population that is being studied is also
called the target population.
A portion of the population selected for
study is referred to as a sample.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Figure 1.1 Population and Sample
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
POPULATION VERSUS SAMPLE
Definition
A survey that includes every member of
the population is called a census. The
technique of collecting information from a
portion of the population is called a
sample survey.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Case Study 1-3 Sample Survey
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
POPULATION VERSUS SAMPLE
Definition
A sample that represents the
characteristics of the population as
closely as possible is called a
representative sample.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
POPULATION VERSUS SAMPLE
Definition
A sample drawn in such a way that each
element of the population has a chance
of being selected is called a random
sample. If all samples of the same size
selected from a population have the
same chance of being selected, we call it
simple random sampling. Such a
sample is called a simple random
sample.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
BASIC TERMS
Definition
An element or member of a sample or
population is a specific subject or object
(for example, a person, firm, item, state,
or country) about which the information
is collected.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
BASIC TERMS
Definition
A variable is a characteristic under
study that assumes different values for
different elements. In contrast to a
variable, the value of a constant is
fixed.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
BASIC TERMS
Definition
The value of a variable for an element is
called an observation or
measurement.
A data set is a collection of observations
on one or more variables.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Table 1.1 Charitable Givings of Six Retailers in
2007
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
TYPES OF VARIABLES
Quantitative Variables
Discrete Variables
Continuous Variables
Qualitative or Categorical Variables
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Quantitative Variables
Definition
A variable that can be measured
numerically is called a quantitative
variable. The data collected on a
quantitative variable are called
quantitative data.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Quantitative Variables: Discrete
Definition
A variable whose values are countable is
called a discrete variable. In other
words, a discrete variable can assume
only certain values with no intermediate
values.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Quantitative Variables: Continuous
Definition
A variable that can assume any
numerical value over a certain interval or
intervals is called a continuous
variable.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Qualitative or Categorical Variables
Definition
A variable that cannot assume a
numerical value but can be classified into
two or more nonnumeric categories is
called a qualitative or categorical
variable. The data collected on such a
variable are called qualitative data.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Figure 1.2 Types of Variables
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
CROSS-SECTION VS. TIME-SERIES DATA
Cross-Section Data
Time-Series Data
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Cross-Section Data
Definition
Data collected on different elements at
the same point in time or for the same
period of time are called cross-section
data.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Table 1.2 Charitable Givings of Six Retailers in
2007
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Time-Series Data
Definition
Data collected on the same element for
the same variable at different points in
time or for different periods of time are
called time-series data.
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Table 1.3 Number of Movie Screens
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
SOURCES OF DATA
Data may be obtained from
Internal Sources
External Sources
Surveys and Experiments
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
SUMMATION NOTATION
A sample of prices of five literary books:
$75, $80, $35, $97, and $88
The variable price of a book: x
Price of the first book = x1 = $75
Price of the second book = x2 = $80
Adding the prices of all five books gives
75+80+35+97+88 = x1+x2+x3+x4+x5 = x
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Example 1-1
Annual salaries (in thousands of dollars)
of four workers are 75, 90, 125, and 61,
respectively. Find
(a) x (b) (x) (c) x
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Example 1-1: Solution
(a) x = x1 + x2 + x3 + x4
= 75 + 90 + 125 + 61
= 351 = $351,000
(b) (x) = (351) = 123,201
(c) x = (75) + (90) + (125) + (61)
= 5,625 + 8,100 + 15,625 + 3,721
= 33,071
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Example 1-2
The following table lists four pairs of m and
f values:
Compute the following:
(a) m (b) f (c) mf (d) mf
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
Example 1-2: Solution
Table 1.4
(a) (b) (c) (d)
Prem Mann, Introductory Statistics, 7/E
Copyright 2010 John Wiley & Sons. All right reserved
