Hi, I ran parallel growth curve process for my dissertation and I got good fit indices. DATA: FILE IS "F:\files in the floppy disk\ANALYSES DISSERTATION backup \DATA WITH LATE ADDITION\growth curve.dat";
I got the means for the intercepts, slopes, variances around the intercepts, and intercept1 on slope 2 and intercept 2 on slope 1. However, Mplus also had an error message "THE LATENT VARIABLE COVARIANCE MATRIX (PSI) IS NOT POSITIVE DEFINITE. This could indicate a negative variance/residual variance for a latent variable" My first construct has a linear decrease across time so the residual variance is indeed negative. Do I need to worry about this error message or may I present this output?
No variance or residual variance estimate should be negative. This makes the model inadmissible. If your outcome decreases over time, this is seen in the negative mean of the slope growth factor not in a negative residual variance.