covariance

詳細解釋：

co.var.i.ance

n.（名詞）
A statistical measure of the variance of two random variables that are observed or measured in the same mean time period. This measure is equal to the product of the deviations of corresponding values of the two variables for their respective means.
協方差：在觀察或測量同一平均時間的兩個任意變數的變化的一個統計值。這個值等於這兩變數的各自平均值偏離其相應值的乘積