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Tengiat Loi posted on Tuesday, September 18, 2018 - 5:49 pm
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Dear Prof. Muthen, I have wrote a Mplus syntax for a 1-1-1 multilevel model in which a path is moderated by w and b path is moderated by z. I am concerned about whether cab is considered covariance or residual covariance. If that's is residual covariance, how should we compute it in model constraint and model it in the mediation? WITHIN = x ; between = w z; CLUSTER = id; ANALYSIS: TYPE = twolevel random; ESTIMATOR = mlr; MODEL: %WITHIN% sc | y ON x; sa | m ON x; sb | y ON m; %BETWEEN% sa sb sc m y w z ; m on w; y on z; sa on w(a2); sb on z (b2); sa with sb (cab); sa with sc m y; sb with sc m y; sc with m y; m with y; [sa](a1); [sb](b1); [w](wmean); [z](zmean); MODEL CONSTRAINT: NEW(saMean sbMean Windlow Windhigh Zindlow Zindhigh); saMean = a1+a2*wmean; sbMean = b1+b2*zmean; Windlow = (saMean+a2*LowW)*sbMean+cab; Windhigh = (saMean+a2*HighW)*sbMean+cab; Zindlow = saMean*(sbMean+b2*LowZ)+cab; Zindhigh = saMean*(sbMean+b2*HighZ)+cab; |
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Why don't you grandmean center w and z so that their means are zero. The cab parameter is the residual variance but that is the relevant variance because you are considering effects conditional on w and z. |
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Tengiat Loi posted on Wednesday, September 19, 2018 - 7:03 pm
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Thank you very much Bengt! |
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Tengiat Loi posted on Tuesday, April 09, 2019 - 1:45 pm
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Dr. Muthen, Should I group mean center m and y before transferring the data to mplus file? I ask because the centering function define: center m and y(groupmean) is not allowed once they are specified at between level. |
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No, you should not group-mean center DVs used on the Within level. A latent variable decomposition is already made for these variables in that their random intercepts vary on Between. |
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