Introduction
Arithmetic mean
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.
