On Wed, 2 Jun 2004, Lutz Ph. Breitling wrote:
Dear all,
i am trying to redo the 'eyestudy' analysis presented on the site http://www.ats.ucla.edu/stat/stata/faq/relative_risk.htm with R (1.9.0), with special interest in the section on "relative risk estimation by poisson regression with robust error variance".
so i guess rlm is the function to use. but what is its equivalent to the glm's argument "family" to indicate 'poisson'? or am i somehow totally wrong and this is not applicable here?
No, no. You want glm() and then a function to compute the robust covariance matrix (there's robcov() in the Hmisc package), or use gee() from the "gee" package or geese() from "geepack" with independence working correlation.
Slight correction: robcov in the Design package, can easily be used with Design's glmD function. -Frank
These are not outlier-resistant estimates of the regression coefficients, they are model-agnostic estimates of the standard errors.
Stata is unusual in providing these covariance matrix estimates for just about every regression estimator. I think R should consider doing something similar, but haven't got around to it.
-thomas
thx a lot- lutz
============================= Lutz Ph. Breitling, CMd
Thomas Lumley Assoc. Professor, Biostatistics [EMAIL PROTECTED] University of Washington, Seattle
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Frank E Harrell Jr Professor and Chair School of Medicine
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