A compound bar chart is a bar graph with secondary and tertiary information measured on the same bar often with a colored key. A bar graph measures frequency data. Compound bar charts are also referred to as stacked bar charts and component bar charts.
The height of a specific bar in a compound bar chart indicates the frequency recorded, simplifying the data into a more digestible medium. A compound bar chart can record extra information; for example, if a basic bar graph represents the data for a class's grades on a bar graph, then it would only show the number of students who obtained specific marks. A compound bar chart can also show the gender of the students in the class, portraying the ratio of the bars using a color for males and a color for females.