Lauretta J. Fox
A frequency distribution can be represented graphically on a
histogram
. A histogram is a bar graph on which the bars are adjacent to each other with no space between them. To construct a histogram, arrange the data in equal intervals. Represent the frequencies along the vertical axis and the scores along the horizontal axis. The true limits of any interval extend one half unit beyond the endpoints established for the interval and are represented in this manner on the horizontal axis. For example, the true limits of the interval 76-80 are 75.5 and 80.5. To get the proper perspective, the vertical axis should be approximately three-fourths as long as the horizontal axis.
Example
:
Illustrate the following set of measurements on a histogram:
72
|
82
|
56
|
73
|
87
|
89
|
72
|
86
|
88
|
76
|
86
|
69
|
84
|
85
|
62
|
97
|
70
|
78
|
84
|
93
|
70
|
60
|
91
|
76
|
83
|
94
|
65
|
72
|
92
|
81
|
98
|
78
|
88
|
76
|
96
|
89
|
90
|
83
|
74
|
80
|
Solution
:
Scores
|
Frequency
|
96-100
|
3
|
91-95
|
3
|
86-90
|
4
|
81-85
|
6
|
76-80
|
8
|
71-75
|
5
|
66-70
|
3
|
61-65
|
2
|
56-60
(figure available in print form)
Exercises
:
-
1.) Construct a histogram for the following scores earned by a group of high school students on a Scholastic Aptitude Examination.
Score
|
Number
of
Students
|
400-449
|
20
|
450-499
|
35
|
500-549
|
50
|
550-599
|
50
|
600-649
|
40
|
650-699
|
20
|
700-749
|
10
|
-
2.) The weights of 40 football players are as follows:
210
|
181
|
192
|
164
|
170
|
186
|
205
|
194
|
178
|
161
|
175
|
195
|
172
|
188
|
196
|
182
|
206
|
188
|
165
|
202
|
178
|
163
|
190
|
198
|
187
|
198
|
174
|
172
|
183
|
208
|
185
|
162
|
203
|
172
|
196
|
184
|
185
|
176
|
197
|
184
|
a.) Construct a frequency distribution for the given data.
b.) Make a histogram for the given data.