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Re: st: Incidence rate ratio


From   Svend Juul <SJ@SOCI.AU.DK>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Incidence rate ratio
Date   Thu, 6 Mar 2008 16:50:39 +0100

Mohammed El Faramawi wrote:
 
I am trying to calculate the incidence rate ratio(IRR)
for a categorical variable ( Mortality) which  has
two categories only ( dead or alive) in a probability
weighted sample. I am also trying to adjust for
covariates. I know that poisson regression can be used
to calculate  (IRR) and adjust for covariates given
that the outcome is  a count for example the number of
deaths, number stroke attacks, etc . My question is
what regression should I use  in such a situation i.e
outcome which is not count.Can I still use poisson
regression which I doubt it?? Thank you
 
---------------------------------------------------------------------
 
You can use the -poisson- command with individual or aggregated data;
the examples in the manual and the help file are with aggregated data, 
but the command works fine with individual data, coded 1 for dead and
0 for alive. To estimate the incidence rate ratio, each individual's
time at risk should also be recorded, here as the variable -risktime-.
 
Example:
 
  . poisson died x1 x2 x3, exposure(risktime) irr
 
Hope this helps,
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:        sj@soci.au.dk 
_________________________________________________________ 


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