Measures of Central Location and Measures of Dispersion

When analysing data, we frequently have more numbers than we can comfortably cope with, and very often the first job is to try to cut down the amount of information that we have.

There are many ways of doing this, but one way is to try to summarise the entire data set by using just a few numbers to represent it, so that these numbers can be used in further calculations or quoted by people, such as politicians.

Needless to say, any old numbers won’t do, and over the years several different methods have evolved. These fall into two main categories: measures of central location (or tendency) and measures of dispersion.