Question

Why is it necessary to measure dispersion to describe a data set?

Answer 1

To describe a data se, it is necessary to measure dispersion in order to quantify how far the data is spread around the average value. The more the dispersion is the less consistent it is.

Range is a measure of dispersion and is given by:

Ragne = meximum value - minimum value.

Example:
Consider marks obtained by two students A and B in five exams as follows:
A : 10,90,70,85,65

B: 40,30,50,45,55

Range of A = 90 - 10 = 80.

Range of B = 55 - 30 = 25

We note that Range of B = 25 is less than Range of A = 80. This shows B is more consistent than A.