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
andrewamiles@hotmail.com.

Andrew Miles

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