Hi, I recently tried to estimate a linear unconditional latent growth curve on 7 repeated measures using lavaan (most recent version):
modspec=' alpha =~ 1*read_g0 + 1*read_g1 + 1*read_g2 + 1*read_g3 + 1*read_g4 + 1*read_g5 + 1*read_g6 beta =~ 0*read_g0 + 1*read_g1 + 2*read_g2 + 3*read_g3 + 4*read_g4 + 5*read_g5 + 6*read_g6 ' gmod=lavaan(modspec, data=math, meanstructure=T, int.ov.free=F, int.lv.free= T, auto.var=T, auto.cov.lv.x=T, auto.cov.y=T, missing="direct", verbose=T) The model immediately returned the following error message: Error in chol.default(S) : the leading minor of order 5 is not positive definite Error in lavSampleStatsFromData(Data = lavaanData, rescale = (lavaanOptions$estimator == : lavaan ERROR: sample covariance can not be inverted I ran the same model in Mplus and found that it has low covariance coverage for the 7 repeated measures, but all coverage is greater than 0. The model ran fine in Mplus once I set the covariance coverage limit to .001. That provided me starting values to try in lavaan, but again it immediately returned the same error message. In fact, nothing I could do allowed me to fit the model without it immediately returning the same error message (e.g., I tried changing the optimizer, the type of likelihood being used). Because the error message pops up immediately (i.e., not after lavaan tries to estimate the model for a few seconds), it makes me think that my data is failing some sort of initial data check. Any ideas what is happening, or what to do about it? Thanks. P.S. I haven't had success in attaching data files when I submit to the R help list, so if you would like the data please email me at [email protected]. Andrew Miles [[alternative HTML version deleted]] ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
