Data Representations and Visualisation

• Construction of grouped frequency distribution table:

There are two ways to group the data to make frequency distribution table. These are as follows:

Inclusive method (Discontinuous form):

The classes can be defined in inclusive method as 1 - 10, 11 - 20, 21 - 30 and 31 - 40. Here, both limits are inclusive in each class.  

Exclusive method (Continuous form):

In exclusive method, we take the class intervals as 0 – 10, 10 – 20, 20 – 30. The observations which are more than 0 but less than 10 will come under the group 0 – 10; the numbers which are more than 10 but less than 20 will come under the group 10 – 20 and so on. Here, the common observation will belong to the higher class, i.e. 10 will be included in the class interval 10 – 20 and similarly we follow this for the other observations also.

For example, the ages of some residents of a particular locality are given as follows:

7, 28, 30, 32, 18, 19, 37, 36, 14, 27, 12, 8, 17, 24, 22, 2, 21, 5, 21, 36, 38, 25, 10, 25, 9.

Frequency distribution table can be drawn as follows:

Inclusive method:

Class intervals	Tally marks	Frequency
1 – 10		6
11 …