# Frequency distribution

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Definition
 Frequency Distribution A tabulation of data values that displays the number of times each value or group of values occurs in the dataset. If the data values are members of a continuous quantitative variable, the values are usually grouped into class intervals. Used in the creation of histograms. Also called frequency table.

## Examples

Pulse rates, in beats per minute, were calculated for $192$ students enrolled in a statistics course at the University of Adelaide.[1] The following table provides the count and percent for the data values grouped into class intervals.

Pulse Rate for a Sample of Students
from the University of Adelaide
Pulse Rate Count Percent
(34-41] 2 1.0%
(41-48] 2 1.0%
(48-55] 4 2.1%
(55-62] 19 9.9%
(62-69] 40 20.8%
(69-76] 53 27.6%
(76-83] 30 15.6%
(83-90] 27 14.1%
(90-97] 10 5.2%
(97-104] 5 2.6%
Total 192 100.0%
Tip: It is very important that each observation be counted only in one interval. However, in the frequency table above, it seems like an observation that borders on two intervals is included in both, because the upper limit of each interval is also the lower limit of the next interval. To avoid double counting observations, the intervals are written to communicate when the limit is included and when it is not. The square bracket means "including" and the parenthesis means "not including". For example, $(69-76]$ is the interval from $69$ to $76$, not including $69$, but including $76$. That is, data values are included in this range when $\ 69 \lt data\ value \le 76\,$.

# Web Resources

### Notes

1. See the dataset, survey, available in the MASS package in R, an open source statistical computing software application.