Variance
Definition
A measure of dispersion equal to the average of the squared deviations of each data point from the mean. Formula: σ² = Σ(xᵢ − x̄)² / n. Standard Deviation = √Variance.
Example
"For data 2, 4, 4, 4, 5, 5, 7, 9 (Mean = 5), Variance = [(2-5)²+(4-5)²+...+(9-5)²]/8 = 4. Standard Deviation = √4 = 2."