[R-sig-ME] Question glmmADMB

Wouter Broos Wouter.Broos at UGent.be
Fri Jun 16 11:02:39 CEST 2017

 Dear Professor Bolker,

 At the moment, I am working on a data set that contains
 information on 'number of errors' that are made by participants. Thus
 far, I used poisson regression to create generalized mixed effects
 models of the data. In order to use poisson regression I aggregated the
 data set by participant and by category. There are eight different
 categories in total (I've added the data for ease of reference). There
 are three main factors that determine the category: 1. Outcome: The
 error that is made can be lexical or non-lexical / 2. Context: The
 context of the block where the error was made can be mixed or
 non-lexical / 3. Language: The language in which the error is made can
 be the first language (L1) or the second language (L2). So, the
 dependent variable in the model is 'Number of Errors' and the fixed
 factors are 'Outcome', 'Context', and 'Language'. All factors
 interaction with one another. One potential problem with the data set is
 that there is an imbalance in the number of '0 number of errors per
 category' and the '1/2/3 number of errors'. However, the zeros in my
 data set can be explained in only one way: no mistake was made by that
 participant in that category. So my first question is: do I need to add
 the zero-inflation component to the model?

 I tried using the glmmADMB package that can take zero-inflation into
 account in order to see whether there are differences with the normal
 poisson model and the zero-inflated model. However, when I ran the
 model, I got the error:

 *Parameters were estimated, but standard errors were not: the most
 likely problem is that the curvature at MLE was zero or negative*

 *Error in glmmadmb(Num_Mistakes ~ (Context * Outcome) + (1 | Subject),  : *

 *  The function maximizer failed (couldn't find parameter file)
 Troubleshooting steps include (1) run with 'save.dir' set and inspect
 output files; (2) change run parameters: see '?admbControl';(3) re-run
 with debug=TRUE for more information on failure mode*

 *In addition: Warning message:*

 *running command 'C:\WINDOWS\system32\cmd.exe /c glmmadmb -maxfn 500
 -maxph 5 -noinit -shess' had status 1*

 I tried leaving out one or two factors, googled the problem and tried
 several 'solutions' but nothing works. So my second question is: how can
 I solve this problem? I also used other packages where zero-inflation
 could also be inserted (glmmTMB and mgcv). When I run the glmmTMB model,
 zero-inflation works (but only for the interaction Context*Outcome, not
 when I try to include Language) but the standard errors for the
 zero-inflated model are rather large (and huge for the interaction)
 leading to p-values of 1. An additional problem with glmmTMB is that I
 cannot use all three factors because there are 'extreme or very small
 eigenvalues'. The R-script is added as an attachment to the e-mail so
 that you can see what I did. Would you be willing to help me out or do
 you have any suggestions as to what I can do next? Thank you.

 Kind regards,

 Wouter Broos?

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