Histogram



         


In statistics, a histogram is a

Histogram of travel time, US 2000 census. Area under the curve equals the total number of cases.

Now the same data are shown in a slightly different fashion. The area of each bar is equal to the proportion of people, of all the people in the survey, who fall into that category. So the total area of all the bars is equal to 1.

Interval Width No. in interval (No. in interval)/(total no.)/width
0 5 4,180 0.0067
5 5 13,687 0.0220
10 5 18,618 0.0300
15 5 19,634 0.0316
20 5 17,981 0.0289
25 5 7,190 0.0115
30 5 16,369 0.0263
35 5 3,212 0.0051
40 5 4,122 0.0066
45 15 9,200 0.0049
60 30 6,461 0.0017
90 60 3,435 0.0004

The preceding table is displayed graphically by the following diagram. The second figure differs from the first only in the vertical scale. Which figure should be used depends on the purpose of the histogram; if the absolute numbers are important, then the first form is more useful, and the second form is more useful if proportions are important.


Histogram of travel time, US 2000 census. Area under the curve equals 1.
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