histogram

Definition

Step-column chart that displays a summary of the variations in (frequency distribution of) quantities (called Classes) that fall within certain lower and upper limits in a set of data. Classes are measured on the horizontal ('X') axis, and the number of times they occur (or the percentages of their occurrences) are measured on the vertical ('Y') axis. To construct a histogram, rectangles or blocks are drawn on the x-axis (without any spaces between them) whose areas are proportional to the classes they represent. Histograms (and histographs) are used commonly where the subject item is discrete (such as the number of students in a school) instead of being continuous (such as the variations in their heights). Also called frequency diagram, a histogram is usually preferred over a histograph where the number of classes is less than eight.