[R] Relative Risk in logistic regression

[Kevin E. Thorpe]

On 01/30/2013 11:26 AM, John Sorkin wrote:
> If you use a log link, you are not, I believe, performing a logistic
> regression!

I guess strictly speaking, that is true.  I was being a little sloppy in 
terminology.

>
> "Kevin E. Thorpe" <kevin.thorpe at 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.thorpe at 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.fan at gmail.com> wrote:
>  >  >
>  >  >
>  >  > From: aminreza Aamini <amin.r.fan at gmail.com>
>  >  > Subject: [R] Relative Risk in logistic regression
>  >  > To: "R-help" <R-help at 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.
>  >  >
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>  >  >
>  >  >


-- 
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.thorpe at utoronto.ca  Tel: 416.864.5776  Fax: 416.864.3016