2/3/2010
1
Chapter 2
Frequency Distributions
PowerPoint Lecture Slides
Essentials of Statistics for the Behavioral
Sciences
Seventh Edition
by Frederick J Gravetter and Larry B. Wallnau
Chapter 2 Learning Outcomes
• Understand frequency distribution
1
•Organize data into regular frequency distribution
2
3
• Organize data into grouped frequency distribution
• Understand data presented in a table
4
•Organize data into frequency distribution graphs
5
• Understand data that presented in a graph
6
Introduction to Frequency
Distributions
•A
frequency distribution
is
– An organized tabulation
– Showing the number of individuals located in
each category on the scale of measuremen
each category on the scale of measurement
• Can be either a
table
or a
graph
• Always shows
– The categories that make up the scale
– The frequency, or number of individuals, in
each category
Xf
8
7
10
9
6
4
9
8
7
8
1. Determine the number
of scores (N)
2. Find the highest and
lowest values
3. List all possible values
even if there are no
scores in that category
4
List from highest to
10
9
8
6
9
7
8
8
4. List from highest to
lowest
5. Find frequency
associated with that
value (f)
how many
people got that score
6. Double check your
math
Adding up the Scores
• In order to calculate anything we still need to
be able to sum (
Σ
) the scores.
Lk
l
it
d
b
t
• Looks complicated but. . .
•
Σ
f = N
•
Σ
fx =
Σ
x
for a frequency distribution
Proportion and Percent
• Proportion—fraction of the total group associated
with each score.
N
f
p
=
• Percent
)
100
(
)
100
(
N
f
p
=
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Frequency, Proportion
and Percent in a Table
Xf
p
= f/N
percent = p(100)
51
1/10 = .10
10%
4
2
2/10 = 20
20%
2/10
.20
33
4/10 = .40
40%
23
0/10 = .00
0%
11
1/10 = .10
10%
This is an adaptation of example 2.3
Learning Check
• Use the Frequency Distribution
Table to determine how many
subjects were in the study
X
f
52
44
31
20
13
•
10
A
•
15
B
•
33
C
•
Impossible to determine from table
D
Learning Check  Answer
• Use the Frequency Distribution
Table to determine how many
subjects were in the study
X
f
•
10
A
•
15
B
•
33
C
•
Impossible to determine from table
D
Learning Check
• Is each of these statements
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 Spring '08
 Delaney
 Psychology, Frequency distribution, Behavioral Sciences

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