Time-invariant latent variable intera... PreviousNext
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 Tim Bednall posted on Thursday, September 06, 2018 - 11:04 am
Hi folks,

I'm trying to estimate a ridiculously complicated longitudinal model, with 8 latent variables measured at 4 occasions. (It is a scalar invariance model, with corresponding factor loadings / intercepts constrained to be equal over time.)

The longitudinal model that I am using is a random intercepts cross-lagged panel model (Hamaker et al., 2015). I am trying to estimate a 3-way interaction between three of the time-invariant (trait-like) variables using the XWITH command. After what seemed like a promising start, the model failed to converge.

I considered a couple of workarounds, but I'm not sure how legitimate they are. The first was to calculate plausible values to represent the latent variables, and to use these in a follow-up analysis.

The second workaround was to estimate the model without the latent interactions, and to retain the model parameter estimates (using the OUTPUT: SVALUES command). I then ran the XWITH model using these SVALUES as fixed parameters, with the exception of the main effects, interactions, and residual variances/covariances of the variables predicted by the interactions. This enabled the model to converge, and the estimated main effects / interactions seemed to be sensible.

I would be keen to hear whether other people have encountered similar difficulties, and how best to deal with it.

Best wishes,

Tim
 Bengt O. Muthen posted on Thursday, September 06, 2018 - 3:32 pm
As a first step, try to get the original run to converge by checking the FAQ on our website:

TECH8 negative ABS changes

If that doesn't work, send output and data to support along with your license number.
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