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....@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 <i...@aghmed.fsnet.co.uk>wrote: > At 10:49 30/01/2013, aminreza Aamini wrote: > >> Hi all, >> I am very grateful to all those who write to me >> 1) how i can obtain relative risk (risk ratio) in logistic regression >> in R. >> > > @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<http://www.bepress.com/uwbiostat/paper293> > } > > } > > > 2) how to obtain the predicted risk for a certain individual using >> fitted regression model in R. >> >> Many thanks, in advance, for your help. >> >> Amin. >> > > Michael Dewey > i...@aghmed.fsnet.co.uk > http://www.aghmed.fsnet.co.uk/**home.html<http://www.aghmed.fsnet.co.uk/home.html> > > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Confidentiality Statement: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message.
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