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st: ST: RE: oddsrisk version 2


From   Jhilbe@aol.com
To   statalist@hsphsun2.harvard.edu
Subject   st: ST: RE: oddsrisk version 2
Date   Sat, 2 Feb 2008 14:51:02 EST

I have been asked by various StataListers to add certain options to the  
-oddsrisk- 
program that I posted to SSC in December. I have submitted the revised  
command 
and help file to Kit for re-posting.
 
The new oddsrisk program now has -if- and -in- capabilities and allows  
frequency weights.
This is important if one wishes to estimate odds and risk ratios directly  
from a 2 x 2 
table. Of course, Stata has a several commands that can be used to  calculate 
risk 
ratios and CIs (using Woolfe's method) from a 2x2 table; eg -csi-. The  
option has been 
added to allow users to model estimated risk ratios from both full and  
tabulated data. 
 
For example, given a 2x2 table of  -death- (response) and -anterior-  (risk 
factor or exposure), 
you would model death on anterior as:
 
            oddsrisk  death anterior [fw=count]
 
A listing of odds ratio, estimated risk ratio, and estimated 95% risk ratio  
CI's are displayed.
If oddsrisk is used on the complete data set, the command would be
 
            oddsrisk  death anterior
 
without the need for a frequency weight of counts.
 
Care must be taken when using -oddsrisk- to estimate relative risk ratios  
for a number of 
predictors; i.e., a risk factor and confounders. There is evidence that  
confidence intervals are 
biased. However, the bias appears to be relatively minimal and the values  do 
not vary 
appreciably from CIs from a Poisson with robust SE or log-binomial. All  
three methods are 
close approximations of the risk ratio and corresponding CIs.  References are 
given in the help 
file. 
 
Joseph Hilbe
 
 



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