Class-Interval

Class interval is a term that is used to denote the numerical width of a class in a frequency distribution. In a grouped frequency distribution, data is arranged in the form of a class. The difference between the upper-class limit and the lower limit gives the class interval.

Definition

A class interval can be defined as the difference between the upper and lower class limit of a frequency distribution table. In other words, it is the width of each class.

Example: Suppose there is a class given by 11 - 21. 11 will be known as the lower class limit while 21 is the upper limit. The class interval is given by 21 - 11 = 10.

Class interval formula

Class interval = Upper Limit - Lower Limit.