(i) Variate:- Any character which consists of several values is called Variate.

(ii) Class interval:- A Group in which Raw data is condensed is called class-interval.

(iii) Class size:- The difference between true upper limit and true lower limit is termed as class-size.

(iv) Class mark:- it is given as

(v) Class limit:- each class is bounded by two figures which termed as class limits.

(vi) True class limits:- in exclusive form of distribution, true lower limit of a class is obtained by subtracting from lower limit and true upper limit is obtained by adding 0.5 to the upper limit.

(vii) Frequency of a class:- Number of data values that fall in the range specified by that class is called frequency of that class.

(viii) Cumulative frequency of a class:- The cumulative Frequency corresponding to that class is the sum of all frequencies up to and including that class.