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Re: st: xtmixed with nonrtolerance. What happens?

From   Maarten Buis <>
Subject   Re: st: xtmixed with nonrtolerance. What happens?
Date   Fri, 24 Jun 2011 09:31:43 +0200

--- "Lukas Boesch"  wrote:
>> The dependent variable is export. The export of wild animal and plant
>> products from one country to the rest of the world. For example: US export of
>> Bears in 1992: 72.
>> Because I cannot sum up the export of different species to one export
>> figure, obviously bears and pearls are not the same, i have to deal with
>> those mixed models. Socioeconomic factors are set as fixed effects and the
>> genus and countries as the variable effects.
>> As one species can be exported by different countries, the data is not
>> hierarchic and country and genus are cross-classified. Or i think this is
>> what it means. Two random effects at the same level for all observations.

I think that your dependent variable is the main reason why your model
is not converging. It is a count and it will probably suffer from lots
of 0s. In that case I would try using -xtmepoisson-. I suspect it will
still not adequately capture the zeros, but it will be better than the
linear model you used.

Hope this helps,

Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
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