Tim wrote,
I wonder if I could ask a more theoretical question: I've calculated the
confidence interval using the Poisson regression method as suggested. The
confidence intervals were consistently smaller than the ones given by
stir.
---------------------------------------------
-poisson- calculates an approximate (asymptotic) confidence interval, and especially if you have few events there can be some discrepancy between the "exact" interval calculated by -ir- and -stir-, and the result from -poisson-. The exact interval should, I think, be preferred. But you can only obtain it in simple situations, not when more independent variables are involved.
Svend
________________________________________________________
Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6
DK-8000 Aarhus C, Denmark
Phone, work: +45 8942 6090
Phone, home: +45 8693 7796
Fax: +45 8613 1580
E-mail: [email protected]
_________________________________________________________
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