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 Robert Latzman posted on Saturday, March 02, 2013 - 6:22 pm
Hello,

I am working on some measurement invariance analyses based on both gender and race and have been running into some trouble. Although the two most restrictive models are running and fitting fine, the two less restrictive models are not. I am receiving the following error message:


THE STANDARD ERRORS OF THE MODEL PARAMETER ESTIMATES COULD NOT BE COMPUTED. THE MODEL MAY NOT BE IDENTIFIED. CHECK YOUR MODEL.PROBLEM INVOLVING PARAMETER 201.

THE CONDITION NUMBER IS -0.577D-09.

There seems to be something wrong with the latent covariance matrix...it seems the matrix is singular (as indicated by the small condition number) leading to two models not being identified. When looking at the parameter estimates, there does not seem to be anything glaringly wrong. Interestingly, the same problem occurs in the PSI matrix when running separate multi-group analyses based on gender and based on race. I have tried fixing the parameter identified as being the problem to 0 but this simply results in the program identifying a different parameter with the same problem in the next run.


Thank you very much for your help with this.
 Linda K. Muthen posted on Saturday, March 02, 2013 - 6:38 pm
I would guess that you are freeing the first factor loading by mentioning it in the group-specific MODEL commands. You should not do that, for example,

MODEL:
f BY y1 y2 y3;

MODEL male:
f BY y2 y3;

If this is not the case, please send the output and your license number to support@statmodel.com.
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