{\displaystyle {\frac {\sum _{i}n_{i}({\overline {Y}}_{i}-{\overline {Y}}_{total})^{2}}{k-1}}} 組內均方WMSS(within means sumofsquares): W M S S {\displaystyle
(回归系数)的方法是普通最小二乘法(英語:ordinary least squares,簡稱OLS),它基於誤差值之上。用這種方法估计 β {\displaystyle \beta } ,首先要計算残差平方和(residual sumofsquares;RSS),RSS是指将所有误差值的平方加起來得出的数: R