Answer to Question #101374 in Statistics and Probability for nimra

Question

(W) how many classes should frequency distribution have? why should the class width be an odd number?

Answer 1

The purpose of frequency distribution is to show shy shape or skew present in data. There is no any fixed rule about number of classes required for a frequency distribution. Actually we need to take it enough number so the shape or trend can be observed. Still we normally use 5 to 20 classes to create a frequency distribution.

Again it is not necessary to use odd numbers only as class width. But if we use odd number then we can get the mid point of class up to same decimal places as class boundaries. It will be helpful in calculating mean, median or standard deviations as it will make calculations easy.