Answers for "variance meaning"

variance

Var(X) = E(X^2) - (E(X))^2

The mean of the squares subtracted by the square of the mean.

variance

Var(X) = E[(X-mu)^2]
Var(X) = Cov(X,X)
Var(X) = E[X^2]-(E[X])^2
Var(X) = E[(X-E[X])^2]

omogeneity of variance

The assumption of homogeneity of variance is an assumption of the independent samples t-test and ANOVA 
stating that all comparison groups have the same variance.