[R] depmixs4 standardError() issue

[Heather Lucas]

Hello,

I've been enjoying using the "Mixture and Hidden Markov Models in R" by Visser & Speekenbrink to learn how to apply these analyses to my own data using depmixS4.

I currently have a fitted 4-state mixture model with three emissions variables and one binomial covariate (HS). I am trying to compute confidence intervals using the following code, where fmms4s is the model:

fmms4Svov <- vcov(fmms4S)$vcov  #this line runs fine
fmms4Sse <- standardError(fmms4S)  #this is where I get the error
fmms4SCI <- confint(fmms4S)

This worked fine before I added the covariate, but with the covariate I receive a warning message: In sqrt(diag(vc$vcov)) : NaNs produced.
As a result, several of my parameters have NaNs as CIs.  In general, I get this error more frequently for more complex models (even when these models converge and show a better fit than simpler models) but I cannot find any information as to why this happens.  Getting rid of one of the emissions variables but leaving the covariate also seems to �fix� the issue but it crops up quite often for me in general.

Many thanks,
Heather

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