The Graphic Presentation of Data

A histogram is a bar chart of data that have been grouped into a frequency distribution.

To construct a frequency polygon, we plot the midpoint of each interval on the x-axis and the absolute frequency for that interval on the y-axis; we then connect neighboring points with a straight line.

Cumulative frequency distribution can plot either the cumulative absolute or cumulative relative frequency against the upper interval limit. The cumulative frequency distribution allows us to see how many or what percent of the observations lie below a certain value.