Intercept in twolevel SEM with latent... PreviousNext
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 Tino Nsenene posted on Tuesday, September 10, 2013 - 5:35 am
Apologies that this will seem like a very simple question, but I'm just finding my way around multilevel SEM using Mplus -
I estimated a twolevel SEM with latent factors (which is conceptually identical to ex.9.6 in the UG). However, I cannot find the intercept of the dependent latent variable (but for the observed indicators). Why is that so, or how could I request the intercept (maybe using model constraint)?

Thank you for your answer!

Tino
 Linda K. Muthen posted on Tuesday, September 10, 2013 - 10:59 am
The intercept/mean of a latent variable in a cross-sectional study is zero. To refer to the intercept, say:

[f];
 Tino Nsenene posted on Thursday, September 12, 2013 - 11:13 am
(referring to my question from 10th september) OK, but if I extend the syntax from ex9.6 using [fb]

MODEL:
%WITHIN%
fw BY y1-y4;
fw ON x1 x2;
%BETWEEN%
fb BY y1-y4;
y1-y4@0;
fb ON w;
[fb];
The following warning appears:
WARNING: THE MODEL ESTIMATION HAS REACHED A SADDLE POINT OR A POINT WHERE THE
OBSERVED AND THE EXPECTED INFORMATION MATRICES DO NOT MATCH.
AN ADJUSTMENT TO THE ESTIMATION OF THE INFORMATION MATRIX HAS BEEN MADE.
THE CONDITION NUMBER IS -0.285D-08.
THE PROBLEM MAY ALSO BE RESOLVED BY DECREASING THE VALUE OF THE
MCONVERGENCE OR LOGCRITERION OPTIONS OR BY CHANGING THE STARTING VALUES
OR BY USING THE MLF ESTIMATOR.

THE STANDARD ERRORS OF THE MODEL PARAMETER ESTIMATES MAY NOT BE
TRUSTWORTHY FOR SOME PARAMETERS DUE TO A NON-POSITIVE DEFINITE
FIRST-ORDER DERIVATIVE PRODUCT MATRIX. THIS MAY BE DUE TO THE STARTING
VALUES BUT MAY ALSO BE AN INDICATION OF MODEL NONIDENTIFICATION. THE
CONDITION NUMBER IS 0.567D-17. PROBLEM INVOLVING PARAMETER 18.



Did I use the syntax incorrectly?
 Linda K. Muthen posted on Thursday, September 12, 2013 - 11:28 am
In a cross-sectional model, the intercept cannot be identified. It is fixed at zero.
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