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本帖最后由 mnczj 于 2013-3-28 11:05 编辑
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5 |' W. \# o5 s# Q* {我发现不少朋友在问Kenny,调节变量是否有去中心化或标准化,Dev K. Dalal 和 Michael J. Zickar 2012年在Organizational Research Method 上专门分析了这个问题。以下是他们的文章摘要。. E6 m9 X! r6 j- ]6 w# C
5 t. n" o2 J* T% `7 d m2 kSome Common Myths About Centering Predictor Variables in Moderated Multiple Regression and Polynomial Regression- z! Z0 }" J% X! T% u3 t
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Abstract
3 N7 t: m- I% U& `+ bAdditive transformations are often offered as a remedy for the common problem of collinearity in; n1 E* |) S; L3 }# _
moderated regression and polynomial regression analysis. As the authors demonstrate in this article,
' P! s% N2 c# ~; u& Pmean-centering reduces nonessential collinearity but not essential collinearity. Therefore, in most
# D- B* X/ @6 p/ R+ gcases, mean-centering of predictors does not accomplish its intended goal. In this article, the authors
/ j4 |0 b; h0 ^6 w% ediscuss and explain, through derivation of equations and empirical examples, that mean-centering
/ }: p% x- y# t: S# e9 cchanges lower order regression coefficients but not the highest order coefficients, does not change6 Z1 K- ^3 z" y8 @ [8 T5 |
the fit of regression models, does not impact the power to detect moderating effects, and does not3 M* l3 ]2 @7 X N, `/ _( u
alter the reliability of product terms. The authors outline the positive effects of mean-centering,- }: X( T2 P9 e7 q' G: w. m: X
namely, the increased interpretability of the results and its importance for moderator analysis in0 y0 k/ ^6 P8 a1 y3 V
structural equations and multilevel analysis. It is recommended that researchers center their predictor% X6 D3 E4 f/ S: Q
variables when their variables do not have meaningful zero-points within the range of the variables
, j" v/ V5 t2 u5 O1 ]to assist in interpreting the results.
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