Elementary Statistics (1+1)

4.2.1 Formation of a discrete frequency distribution

The process of preparing this type of distribution is very simple. We have just to count the number of times a particular value is repeated which is called the frequency of that class. In order to facilitate counting prepare a column of “tallies”. In another column, place all possible values of variable from the lowest to the highest. Then put a bar (vertical line) opposite the particular value to which it relates. To facilitate counting, blocks of five bars are prepared and some space is left in between each block. We finally count the number of bars and get frequency.

The process shall be clear from the following examples :

Illustration 1 : In a survey of 35 families in a village, the number of children per family was recorded and the following data was obtained :

1 7 8 7 9

0 2 4 6 7

2 3 5 5 9

3 4 12 3 4

4 0 6 3 5

5 2 3 7 4

6 5 2 8 3

Represent the data in the form of a discrete frequency distribution.

FREQUENCY DISTRIBUTION OF THE NUMBER OF CHILDREN

It is clear from the table that the number of children varies from 0 to 12. There were 2 families with no child, 5 families with 4 children each only one family with 12 children.

Illustration 2 : Count the number of letters in each word of the para given below (ignoring comma, full-stop, etc.) and prepare a discrete frequency distribution.

Today, to a very striking degree, our culture has become a statistical culture. Even a person who may never have heard of an index number, is attached in an intimate fashion by the gyrations of those index numbers which describe the cost of living.

No. of Letters	Tallies	Frequency
1 2 3 4 5 6 7 8 9 10	III IIII I IIII II IIII IIII I I	3 9 6 4 7 5 4 4 1 1

This method of classifying helps in condensing the data only where values are largely repeated, otherwise hardly any condensation will be done.