[R] Logistic Regression in R (SAS -like output)

Frank Harrell
Mon, 09 Aug 2010 12:53:07 -0000

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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