Dear all,

It may be a silly question, but I was unable to resolve it after some time searching the manuals.

Here is a quick example to illustrate my question:

Code:
*! simulate data for a Poisson model
clear
set obs 100
set seed 123456
gen x1 = runiform()
gen xb = 1 + 0.62*x1
gen exb = exp(xb)
gen events = rpoisson(exb)
tab events
gene total_participants = round(rnormal(100,10))
gene lntotal = ln(total)
*! fit the model with an offset -aggregated data
glm events x1 , family(poisson) offset(lntotal)
*! predict mean events at two levels of the predictor
margins, at(x1=(0.25 0.75))
Margins is correctly predicting the mean number of events per exposure level - for the mean of the offset variable, which is 99.9974 participants.

Is there a way to specify any number of participants, say, 70 or 120 instead [something like at(total_participants=100)]?

All the best,

Tiago