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Stat C2

This document discusses frequency distributions and how to construct them. It provides definitions for key terms used in frequency distributions like class interval, class frequency, class mark, and class boundaries. It also outlines the steps to construct a frequency distribution which include arranging data, computing the range and number of classes, determining class size and limits, and tallying data into class intervals. An example is provided showing age data for 100 residents organized into a frequency distribution with calculations for class intervals, frequencies, relative frequencies, and cumulative frequencies.

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18 views13 pages

Stat C2

This document discusses frequency distributions and how to construct them. It provides definitions for key terms used in frequency distributions like class interval, class frequency, class mark, and class boundaries. It also outlines the steps to construct a frequency distribution which include arranging data, computing the range and number of classes, determining class size and limits, and tallying data into class intervals. An example is provided showing age data for 100 residents organized into a frequency distribution with calculations for class intervals, frequencies, relative frequencies, and cumulative frequencies.

Uploaded by

PingotMaganga
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
You are on page 1/ 13

FREQUENCY

DISTRIBUTION

Raw Data: data which


have not been organized
numerically.
Array: an arrangement of raw
numerical data according
to magnitude which
ascending or descending
order.

FREQUENCY DISTRIBUTIONS
Class Interval: grouping defined by a
lower limit and an upper limit.
Class Frequency: the number of
observations belonging to a
class interval.
Class Mark: midpoint or middle
value of the class interval

Class Boundary: the most precise


expressions of the class limits
(true limits)

Class Size: the width of each class


interval

STEPS IN CONSTRUCTING A
FREQUENCY DISTRIBUTION
1. Array the given data in ascending
order.
2. Compute the range.
Range: HS-LS
3. Determine the number of classes by
using the Sturges formula
K=1+3.22 log n
n is the number of observations

Steps..
4. Compute for the class size. C=R/K.
The computed value of C should
be rounded-off for convenience
5. Determine the lowest class limit.
6. Tally each score to the category of
class interval it belongs to. Sum
the frequency and check if its
total is equal to the total number
of observations.

Relative Frequency
Distribution
Denote by % (rf), is defined
by getting the ratio of the
number of items in each class
to the total frequency

Cumulative Frequency
Distribution
the accumulated frequencies of the
classes ; it can be either at the beginning
or end of the distribution.
The less than cumulative frequency
is the number of observations that are
less than the upper class boundary,
The greater than cumulative
frequency is the number of observations
that are greater than the lower class
boundary in a given interval.

Example: Grouped Data


Age (yrs) of 100 Residents of Brgy
New Banican, Olongapo City

14

27

27

23

29

21

20

12

22

17

23

24

18

20

27

16

12

22

19

19

15

20

29

25

24

20

20

17

18

18

12

22

23

17

23

26

16

21

21

20

17

18

26

18

28

27

18

22

19

16

14

16

19

20

20

18

25

19

26

15

28

13

18

17

14

27

24

20

18

25

17

20

23

18

18

24

19

19

14

18

21

21

25

24

14

25

20

17

17

17

15

12

26

23

17

20

24

25

18

15

Solution

1. Arrange the given raw data in ascending


order.

12

12

12

12

13

14

14

14

14

14

15

15

15

15

16

16

16

16

17

17

17

17

17

17

17

17

17

17

18

18

18

18

18

18

18

18

18

18

18

18

18

19

19

19

19

19

19

19

20

20

20

20

20

20

20

20

20

20

20

20

21

21

21

21

21

22

22

22

22

23

23

23

23

23

23

24

24

24

24

24

24

25

25

25

25

25

25

26

26

26

26

27

27

27

27

27

28

28

29

29

Solution
Step 2: Compute the range
range= Highest score-lowest score
Step 3:
K = 1 + 3.322 log n
Step 4: Compute the class size
C = R/K
Step 5: Organize the class interval.
Step 6: Tally each to the category of
class interval it belongs to.

Frequency Distribution of Age (years) of 100


Residents of Banican, Olongapo City
Class
Interval

Frequenc
y

Class
Mark

Class
Boundaries

<cf

>cf

Relative
Frequency

12-13

12.5

11.5-13.5

100

5%

14-15

14.5

13.5-15.5

14

95

9%

16-17

14

18-19

20

20-21

17

22-23

10

24-25

12

26-27

28-29

100

N=100

The End of Chapter 2

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