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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
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