Re: [R] Relative Risk in logistic regression

2013-02-03 Thread Michael Dewey
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

Re: [R] Relative Risk in logistic regression

2013-02-03 Thread aminreza Aamini
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

Re: [R] Relative Risk in logistic regression

2013-02-03 Thread 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

Re: [R] Relative Risk in logistic regression

2013-02-03 Thread David Winsemius
On Feb 3, 2013, at 8:15 AM, aminreza Aamini wrote: 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

Re: [R] Relative Risk in logistic regression

2013-02-01 Thread Ivan-K
Dear colleagues, I have 2 points: One opinion and one question. 1) In one paper in a peer-reviewed journal, I read about the idea of using a logit regression as a surrogate for the log-binomial, just adding the numerator to the denominator ... It’s tempting to immediately get the RR instead of

Re: [R] Relative Risk in logistic regression

2013-02-01 Thread Greg Snow
Ivan, In reference to your part 2), in 1989 Li and Duan published a paper where they examined the effect of using the wrong link function ( http://projecteuclid.org/DPubS?service=UIversion=1.0verb=Displayhandle=euclid.aos/1176347254). The short version is that they found that in common models

Re: [R] Relative Risk in logistic regression

2013-01-31 Thread Frank Harrell
I am curious why one would want risk ratios. Unlike odds ratios, they are not interpretable without reference to the base risk. For example a risk ratio of 2 cannot possibly apply to anyone with a starting risk exceeding 1/2. I think it is most helpful to use one of the existing nomograms to

[R] Relative Risk in logistic regression

2013-01-30 Thread aminreza Aamini
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] Relative Risk in logistic regression

2013-01-30 Thread aminreza Aamini
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.

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread nalluri pratap
Relative risk = exp(coef(model)) --- 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

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread nalluri pratap
)   prediction_error= lm.D90$residuals --- 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

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread Kevin E. Thorpe
] 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

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread John Sorkin
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

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread Kevin E. Thorpe
= 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

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread John Sorkin
, 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

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread Kevin E. Thorpe
(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

Re: [R] Relative Risk in logistic regression

2013-01-30 Thread David Winsemius
On Jan 30, 2013, at 5:49 AM, 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. 2) how to obtain the predicted risk for a certain individual using fitted regression model in R. You