Bar graphs (also called bar charts) are a type of data visualization in which data points are represented by rectangular bars. Typically, the bars extend vertically from the bottom of the x-axis up to the data value, which is plotted along the y-axis; thus, the height of the bar (physical magnitude) is analogous to the numerical magnitude of the data point; bars may also be horizontal with length representing magnitude. Each data point is either labeled along the x-axis or referenced in a legend in a separate location near the graph. This entry discusses how bar graphs are used, factors that affect comprehension of bar graphs, and implications for educational research.

Bar graphs are often used to communicate scientific results, qualitative trends, and statistical analyses, such ...