Formation of Continuous Frequency Distribution: 

 Continuous frequency distribution is most popular in practice. With reference to the formation of this type of frequency distribution the following technical terms are important.

(1) Class Limits:  The two values   which determine the limit of a group are called class class limits. The lower value is called lower limit whereas the higher value is called upper limit. In the example  given on page No5, 10,20,30,40,50,and 70, are  the lower limits of the related group  while 10, 20, 30, 40, 50, and 70 are upper limits of those groups. Lower limit is expressed by the symbol and the upper limit by.

(2) Magnitude of the Interval:  The difference between   the upper and lower limits of a class is called magnitude of the interval. In the aforesaid example the magnitude of each class interval or group is 10. it is expressed by the symbol.

(3) Mid value or midpoint central size: The central place of class limit is called mid value or midpoint or central size. It is obtained by dividing the sum of both the limit with 2 symbolically.

In the aforesaid example the mid value of the first group is  =10+0/2

Mid value = upper limit +lower limit /2

(4) Class Frequency   The number  of items or observation  corresponding to a particular class is known as frequency of that class .In the aforesaid example  the frequency of (0-10) class is 10, (10-20)  class 25 and similarly  .40,50,350,20,and 10 respectively for    (20-30), (30-40),(40-50),(50-60),and (60-70),  groups, The summation of all the  in division class frequencies being  200   is called  total  frequencies or total number of items.