Hi All,

Up to now I have benefitted a lot from this forum. One question I can’t get my head around is the following:
I have a longitudinal dataset in a long-format (the long-format is because I have variables that change every visit a patient comes is). I want to estimate the IR (by1.000) using poisson regression.
#poisson hpvinc i.agec i.smk, exposure(pdomo) irr#
#xtset id#
#xi: xtgee hpvinc i.agec i.smk, exposure(pdomo) eform family(poisson) corr(exc)#
#gen pdomo=(pdo/30.5)/1000#
Because the data is in long-format, would it be better to use GEE to take into account clustering of the individuals records within one id?
Both approaches give almost the same answer, with some subtle differences behind the comma for the IR as well as the 95%CI.
Thanks for your time,
Catharina