I'm doing a twolevel CFA, with teachers nested within schools, and I'm having a couple of problems.
First, I have a dichotomous variable indicating school type, middle school vs not middle school.
With variable in the model, I get the error:
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 -0.502D-18. PROBLEM INVOLVING PARAMETER 29.
(Where parameter 29 is the variance of this variable).
Even if there is nothing else in the model, I get this error.
My model looks like:
model: %within% %between% midschool; [midschool];
However, it appears that it is identified - at least, changing the starting values don't change the answers I get.
There's also a weird thing with the MIs, but I thought it would be clearer if that were in a separate post.