Arithmetic mean
Also: average
The sum of observations divided by their count.
The sample mean estimates a distribution's central value but is sensitive to outliers and does not describe spread.
- Formula
x̄ = Σxᵢ/n
Example Measurements 9, 10, and 11 mm have mean 10 mm.
Common misconception A mean need not be an observed value or represent a multimodal dataset well.