A bar chart is a pictorial representation of the information in a frequency distribution. It displays the classes on the horizontal axis and the frequencies or relative frequencies of the classes on the vertical axis. The height of a bar represents how common a particular value or category is in a distribution. A frequency is the number of observations that fall in a class—that is, counts. A relative frequency is the ratio of the frequency of a class to the total number of observations—that is, the proportion or percentage of cases that fall into a class.

One may create either a frequency or a relative frequency bar chart. A frequency bar chart is a graph that displays the classes on the horizontal axis and the frequencies ...