Introduction
Arithmetic mean
4. Sensitivity to outliers
Median
Mode
Summary

Instruction

The arithmetic mean is sensitive to outliers. See the table below.

Set Sum Arithmetic mean
1,1,1,1 4 1
1,1,1,9 12 3
1,1,1,97 100 25
1,1,1,997 1000 250
1,1,1,-1003 -1000 -250

Changing only one element changes the arithmetic mean. This change can be substantial if the outlier is an extremely large or an extremely small value.

Sensitivity to outliers is a main disadvantage of the arithmetic mean.