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:

# hours worked

4

6

2

8

5

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