The mean, also called the arithmetic mean or the average, is simply the sum of all the data points divided by the number of points. It is denoted with 
. The formula for the mean is:
For example, here are the number of hours that some students worked on a project:
The average time spent working was:
The average is the most common way of calculating central tendency. Some of its characteristics are:
- easy to calculate
- only one exists for any data set
- affected by all observations, and therefore strongly affected by outliers
- used in many statistics calculations
