If you use a log link, you are not, I believe, performing a logistic regression!
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)>>> "Kevin E. Thorpe" <kevin.tho...@utoronto.ca> 1/30/2013 11:22 AM >>> On 01/30/2013 11:17 AM, John Sorkin wrote: > I am not sure why one would want a relative risk from a logistic > regression. The measure of association from a logistic regression is the > odds ratio, not the relative risk. > John > Yes, the natural measure, when using the logit link, is the OR. I always use that myself, but if you use the log link, you get RR. As for why you would, I would suggest it's because physicians think they understand a RR better than and OR. > "Kevin E. Thorpe" <kevin.tho...@utoronto.ca> 1/30/2013 11:14 AM >>> > On 01/30/2013 09:02 AM, nalluri pratap wrote: > > Relative risk = exp(coef(model)) > > > > Only if you fit using the log link. Using the logit link, this gives > odds ratios. > > > --- On Wed, 30/1/13, aminreza Aamini <amin.r....@gmail.com> wrote: > > > > > > From: aminreza Aamini <amin.r....@gmail.com> > > Subject: [R] Relative Risk in logistic regression > > To: "R-help" <R-help@r-project.org> > > Date: Wednesday, 30 January, 2013, 4:19 PM > > > > > > 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. > > 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. > > > > ______________________________________________ > > 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. > > > > [[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. > > > > -- Kevin E. Thorpe Head of Biostatistics, Applied Health Research Centre (AHRC) Li Ka Shing Knowledge Institute of St. Michael's Assistant Professor, Dalla Lana School of Public Health University of Toronto email: kevin.tho...@utoronto.ca Tel: 416.864.5776 Fax: 416.864.3016 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.
______________________________________________ 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.
