5. Classes and class intervals

Until now, we have dealt with data with discrete values. In other words, we have dealt with data finite numbers or data of a countable number of values.

Let us consider a train journey from Chennai to Bangalore. To know more about the kinds of passengers who travel, we are expected to prepare a data table based on their age groups.

For larger data like these, do you think discrete would be enough?

Age is not a discrete number. We are always a day older than the previous day. Hence, quantifiers like age, weight, height, volume and so on are called continuous values, and they also vary from person to person and from region to region.

 

In other words, quantifiers that keep varying are called continuous variables.

 

Varying quantifiers are depicted in the form of class intervals. Class intervals are prevalent only in continuous set of data.

 

Class:

Class interval (C.I.):

\(\text{Class interval} = \text{Upper limit} - \text{Lower limit}\)

 

If, Upper limit \(= 45\) and Lower limit \(= 32\).

 

Then, \(\text{Class interval} = \text{Upper limit} - \text{Lower limit}\)

 

\(= 45 - 32\)

 

\(= 7\)