Hello everyone, im testing over dispersion in a count variable. I'm using Hilbe's book "Negative binomial regression" for the analysis. He used the formula LR = −2(LP − LNB), but calculate it by hand and then used chiprob(1, result)/2. All my independent variables are presence or ausence of drug consumption, that means i have to adjust models separately.

local sus binoh bintab binmar bincoc binpas
foreach var of local sus {
poisson num_psex `var' sexo i.or_sexual i.tramo_etario edad_inicio nse
estimates store m1
nbreg num_psex `var' sexo i.or_sexual i.tramo_etario edad_inicio nse
estimates store m2
lrtest m1 m2
}

test involves different estimators: nbreg vs. poisson

this is what i got. And it make sense because im not using the same function. I need to store the log likelihood of my models and then use the formula, but i dont know how to make it efficient.

Please, i need some ideas. Thank you very much.