ABSTRACT
Grouped data can be presented diagrammatically by:
a histogram, in which the areas of vertical, adjacent rectangles are made proportional to frequencies of the classes,
a frequency polygon, which is the graph produced by plotting frequency against class mid-point values and joining the co-ordinates with straight lines,
a cumulative frequency distribution, which is a table showing the cumulative frequency for each value of upper class boundary, and
an ogive or a cumulative frequency distribution curve, which is a curve obtained by joining the co-ordinates of cumulative frequency (vertically) against upper class boundary (horizontally).
