A.1.6—Mean, median and mode

The mean uses every value, the median is the middle after ordering, and the mode is the most frequent value. The best summary depends on the measurement and its distribution.

Use the median when an outlier would distort the mean; use the mode for common categories or repeated discrete values. Report the raw context and sample size.

Income-like values 2, 2, 3, 3 and 20 have mean 6 but median 3, so the median better represents a typical observation.

No summary statistic tells you the spread or the mechanism producing the data.