I’m using Mplus to conduct LCA with 3 categorical indicators (2 with 3 options and 1 with 2 options) and 5 continuous indicators. I am able to run a 2 and 4 class solution with no errors; however, when I attempt LCA with 3, 5, etc. classes I get the following 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 0.205D-20. PROBLEM INVOLVING PARAMETER 34.
I’ve used tech1 to examine the parameter (an have an issues with C#2 parameter) and have changed start values, and yet this problem persist. Would you have any suggests on how I can ‘fix’ this issues?
Additionally, what are your thoughts about having more classes than variables in the model?