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A measure of centre for a distribution of a numerical variable. The mean is the centre of mass of the values in a distribution and is calculated by adding the values and then dividing this total by the number of values.
For large data sets it is recommended that a calculator or software is used to calculate the mean.
The mean can be influenced by unusually large or unusually small values. It is recommended that a graph of the distribution is used to check the appropriateness of the mean as a measure of centre and to emphasise its meaning as a feature of the distribution.
Example
The maximum temperatures, in degrees Celsius (°C), in Rolleston for the first 10 days in November 2008 were: 18.6, 19.9, 20.6, 19.4, 17.8, 18.1, 17.8, 18.7, 19.6, 18.8
The mean maximum temperature over these 10 days is 18.93°C.
The data and the mean are displayed on the dot plot below.
Alternative: arithmetic mean
See: measure of centre, population mean, sample mean
Curriculum achievement objectives references
Statistical investigation: Levels 5, (6), (7), 8
