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本帖最后由 mnczj 于 2013-3-28 11:05 编辑
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6 E1 A; j; e! f( R9 E# A" S7 a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。
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6 h+ R5 V& n0 c& E( G4 ]& A* ~Some Common Myths About Centering Predictor Variables in Moderated Multiple Regression and Polynomial Regression: r; G- b. C2 |
* }! k0 ]0 J) R9 ]7 C' VAbstract
q4 G$ W. C1 e" ^# s' |& T/ |! V4 z& VAdditive transformations are often offered as a remedy for the common problem of collinearity in* e& Z1 J# }; p8 T4 _7 K+ U3 v
moderated regression and polynomial regression analysis. As the authors demonstrate in this article,; v1 n, Q. h6 c4 u. G6 \
mean-centering reduces nonessential collinearity but not essential collinearity. Therefore, in most7 |0 C5 q9 z& o9 T1 G1 o2 l
cases, mean-centering of predictors does not accomplish its intended goal. In this article, the authors/ j0 M9 _1 j3 Y* _" h
discuss and explain, through derivation of equations and empirical examples, that mean-centering Y0 U" u; t2 b$ {3 C
changes lower order regression coefficients but not the highest order coefficients, does not change: u$ V, `* V0 b$ u) Z3 r8 x
the fit of regression models, does not impact the power to detect moderating effects, and does not
c! E ?5 X' k+ Oalter the reliability of product terms. The authors outline the positive effects of mean-centering,! E. s; n2 d. B8 l
namely, the increased interpretability of the results and its importance for moderator analysis in3 g8 B3 A! `; G" |0 c* P. Y8 B5 {
structural equations and multilevel analysis. It is recommended that researchers center their predictor
, z- i( K, _& P, R- }5 y0 Avariables when their variables do not have meaningful zero-points within the range of the variables
. h, h# h6 p( D/ @6 u+ @7 e. ?, zto assist in interpreting the results.
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