st: GLLAMM problem in comprob3

["P.T.Dijkstra" <p.t.dijkstra@rug.nl>]

Dear all,
While using the GLLAMM package, I sometimes obtain the following error message:
> can't get correct log-likelihood: -31.09976 should be -31.123589
> something went wrong in comprob3
> 


I am under the impression that GLLAMM cannot estimate the model correctly because I have almost no "ones" in the dataset.
There are two groups: group 1 has just 20 times a one out of 970 observations, group 2 has only 2 ones out of 1000 observations.


I try to estimate a group effect as follows:
gllamm success groupeffect if group <= 2, i(personID group) family(binom) link(logit) robust adapt search(25) iterate(250)


The output:
Running adaptive quadrature
Iteration 0:    log likelihood = -37.679599
Iteration 1:    log likelihood = -33.411411
(...)
Iteration 249:    log likelihood = -31.095211
Iteration 250:    log likelihood = -31.195684

Adaptive quadrature has converged, running Newton-Raphson
Iteration 0:   log likelihood = -31.195684  (not concave)
Iteration 1:   log likelihood = -31.135656  
(...)
Iteration 4:   log likelihood = -31.123589  
can't get correct log-likelihood: -31.09976 should be -31.123589
something went wrong in comprob3
r(198);




Does anyone recognize this problem with the same data structure or is there anything else I can do?
I know that this kind of problem has been posted before, but any help is highly appreciated.


Best,
Peter Dijkstra
University of Groningen



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