Frank E Harrell Jr Professor and Chairman School of Medicine
Department of Biostatistics Vanderbilt University
On Mon, 9 Aug 2010, Harsh wrote:
Hello useRs,
I have a problem at hand which I'd think is fairly common amongst
groups were R is being adopted for Analytics in place of SAS.
Users would like to obtain results for logistic regression in R that
they have become accustomed to in SAS.
Towards this end, I was able to propose the Design package in R which
contains many functions to extract the various metrics that SAS
reports.
The replacement for Design, rms, has some new indexes.
If you have suggestions pertaining to other packages, or sample code
that replicates some of the SAS outputs for logistic regression, I
would be glad to hear of them.
Some of the requirements are:
- Stepwise variable selection for logistic regression
an invalid procedure
- Choose base level for factor variables
not relevant - get what you need from predicted values and
differences in predicted values or contrasts - this automatically
takes care of reference cells
> - The Hosmer-Lemeshow statistic
obsolete: low power and sensitive to choice of binning
- concordant and discordant
see Hmisc's rcorr.cens
- Tau C statistic
Those are two different statistics. tau and C are obtained by lrm in
rms/Design.
Frank
Thank you for your suggestions.
Regards,
Harsh Singhal
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and provide commented, minimal, self-contained, reproducible code.
