Median, range, and unusual values

Choose summaries that describe the centre and spread of data.

Find the middle value

Sort the data before finding the median. With an even number of values, take the mean of the two middle values.

Worked example

For 2, 4, 7, 9, the median is (4 + 7) ÷ 2 = 5.5.

The range is the maximum minus the minimum. One unusually large value can strongly affect the mean and range while leaving the median unchanged.

Worked example

For 1, 2, 3, 4, 20: median = 3, mean = 6, range = 19.