Hi StatDave_sas, Thanks for your response. Much appreciated for the links. I think I incorrectly stated «Overall state IRR » . Indeed there is one state (which does not appear in the model), with 10 administrative divisions (whose I considered as cluster). Over the specified period, for each day, in each administrative division, we have the count of persons killed in traffic and the daily mean temperature. So I am modeling the mean daily count of persons killed as function of mean daily temperature. Now, by « overall state IRR », I would like to get the effect for a 1 unit increase in the mean daily temperature for the entire state, as depicted in the first genmod. Likewise, to get the IRR at division level, e.i. the effect for a 1 unit increase in the mean daily temperature for the each division, as depicted in the second genmod. At this point, I came to include the temperature by division interaction in the model in order to get the IRR, but also in the repeated part, being defined as cluster. Now, I am not sure I can get an effect with lsmeans for a single continous variable, like in model 1, unless it involved in an interaction with a categorical variable. Thanks again for your help, I will appreciate any input,
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