Variance
Also: σ²
A measure of squared spread around a mean.
Variance is expected squared deviation and has squared units; inverse variance weights independent unbiased estimates by modeled precision.
- Units
- measurement units squared
- Formula
Var(X)=E[(X−μ)²]
Example A 0.05 m standard deviation corresponds to 0.0025 m² variance.
Common misconception Variance is not standard deviation and cannot be compared without considering units and assumptions.