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Relative Risk in logistic regression

4 messages · Michael Dewey, aminreza Aamini, John Sorkin +1 more

Michael Dewey
#
At 10:49 30/01/2013, aminreza Aamini wrote:
@TECHREPORT{lumley06,
   author = {Lumley, T and Kronmal, R and Ma, S},
   year = 2006,
   title = {Relative risk regression in medical research: models, contrasts,
           estimators, and algorithms},
   number = 293,
   institution = {{UW} Biostatistics Working Paper Series},
   keywords = {glm, Poisson},
   url = {http://www.bepress.com/uwbiostat/paper293}
}
Michael Dewey
info at aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html
John Sorkin
# 
Amin,
It is incorrect to use the relative risk as a measure of association in a logistic regression.  The measure of association in a logistic regression is the odds ratio. The odds ratio is an approximation of the relative risk. The approximation becomes progressively better as the disease becomes progressively rarer. Regardless of whether the disease is rare or not, inferences drawn from a logistic regression are valid. Please do not report a logistic regression using relative risk. It is not correct to do so. 
John  

 
John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)>>> aminreza Aamini <amin.r.fan at gmail.com> 2/3/2013 9:15 AM >>>
Dear Coleagues ,
As my friend John  mentined,* the measure of association from a logistic
regression is the odds ratio, not the relative risk*. but the point is in
follow-up studies, it is commonly preferred to estimate a risk ratio rather
than an odds ratio. Thats why im looking for RR in logistic models.
Bytheway thank you all for ur consideration.
Amin
On Sun, Feb 3, 2013 at 1:42 PM, Michael Dewey <info at aghmed.fsnet.co.uk>wrote:

            

      
      
      
    

        
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      David Winsemius
    

    

      
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On Feb 3, 2013, at 8:15 AM, aminreza Aamini wrote:

        

            

      
      
      
    

        
I agree that the relative risk is generally preferred in presenting  
the results of follow-up studies. The question should be:  why do you  
want to use a logistic link? The technical report out of the  
University of Washington Biostatistics Depeartment explains a variety  
of approaches including using a log-binomial model and Poisson  
regression. Either of those can be done in R with glm. The Poisson  
regression model is particularly simple to develop.  You should  
explain a)  what sort of data you have in greater detail and b) your  
reasons for using the logistic link when arguably better alternatives  
are available if you want a more specific answer.