Bar Charts

A bar chart is used to present categorical, quantitative or discrete data.

The information is presented on a coordinate axis. The values of the variable are represented on the horizontal axis and the absolute, relative or cumulative frequencies are represented on the vertical axis.

The data is represented by bars whose height is proportional to the frequency.


A study has been conducted to determine the blood types of a class of 20 students. The results are as follows:

Blood Type fi
A 6
B 4
AB 1
0 9
Bar Chart

Frequency Polygons

A frequency polygon is formed by joining the tips of the bars (the values of the frequencies) by line segments.


The changes in the temperature on a particular day are represented by the following variations:

Hour Temperature
9 12°
12 14°
15 11°
18 12°
21 10°
Frequency Polygons