I'm working with a Poisson model of weighted survey data. My outcome is ACCESS to a weapon (0/1). I have several predictors, including GENDER (0 female /1 male) and a RISK category (0 = no mental health risk factors / 1 = intermediate risk factors / 2 = severe risk factors). I'd like to test an interaction between GENDER (0/1) and the RISK (0/1/2) categories.

My stata command is: svy, subpop(varname): poisson ACCESS AGE i.RISK i.GENDER i.RISK#i.GENDER varname3, irr

My specific questions are:

1) Is this the proper way to create the interaction term?

2) Why does the stata output only show results for the 1/1 and 1/2 interaction levels (attached below)?

3) Can I appropriately interpret each of the interaction IRR's as the IRR relative to the 0/0 interaction level?

View attachment 4266

I'm unsure why; but if I test the interaction term without the main effect terms, I get results for each interaction level (attached).

My stata command is: svy, subpop(varname): poisson ACCESS AGE i.RISK#i.GENDER varname3, irr

View attachment 4267