Mean centering for interaction terms PreviousNext
Mplus Discussion > Structural Equation Modeling >
 Fay Chen posted on Thursday, April 21, 2016 - 9:40 am
Dear Drs.Muthen,

I am conducting latent interaction analysis in Mplus. Instead of mean centering all indicators in Mplus, I centered the indicators for latent independent variables in R first (x1 through x6) and formed the latent interaction product terms there (i.e., x1x4, x2x5, x3x6). Then in Mplus I centered the x1x4, x2x5 and x3x6 using the CENTERING command before modeling it.

Do you think this is the correct way? Does Mplus automatically center the latent variables, or do I still need to center latent variables manually before modeling it?

I appreciate your help!
 Bengt O. Muthen posted on Friday, April 22, 2016 - 8:46 am
You don't need to do any centering when using XWITH.
 Fay Chen posted on Wednesday, April 27, 2016 - 1:28 pm
Thank you for your suggestion, Dr. Muthen! I am trying to use the unconstrained product indicators approach proposed by Marsh, Wen, & Hau (2004). If I am forming the latent interaction variable using the product indicators from the two latent independent variables, should I simply regress the latent dependent variable on 1)latent IV1, 2)latent IV2, and 3)latent interaction variable as formed using product indicators, or do I need to use the XWITH command?

Below is part of my input dealing with the interaction using the product indicators approach. Do you think this is correct, or should I use XWITH somewhere for the interaction? Thank you so much!

VARIABLE: NAMES ARE y1 y2 y3 x1 x2 x3 x4 x5 x6;
usev = y1 y2 y3 x1 x2 x3 x4 x5 x6 x1x4 x2x5 x3x6;
CENTER = grand mean (x1 x2 x3 x4 x5 x6);
x1x4 = x1*x4;
x2x5 = x2*x5;
x3x6 = x3*x6;

MODEL: ksi1 BY x1 (L1)
x2 (L2)
x3 (L3);

ksi2 BY x4 (L4)
x5 (L5)
x6 (L6);

ksi1ksi2 BY x1x4 (L7)
x2x5 (L8)
x3x6 (L9);

eta BY y1 y2 y3;

eta ON ksi1 ksi2 ksi1ksi2;
 Bengt O. Muthen posted on Friday, April 29, 2016 - 6:57 pm
Sorry, I have not used the unconstrained product indicators approach - you may want to ask on SEMNET. Why not use XWITH.
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