(-)均值 x1+x,+…+xn1 x ∑ x 模比系数: XC K,+K+,+K K K WUHEEWUHEE （一）均值 模比系数： = = + + + = n i i n x n n x x x x 1 1 2 ... 1 x xi = = + + + = n i i n K n n K K K K 1 1 2 ... 1