Somers Dyx
Tyler, The rcorr.cens, rcorrp.cens, and somers2 functions compute Dxy. That is a typo in the overview, which we'll fix. Dxy is the appropriate measure for binary Y, I think. It is a simple translation of the ROC area and does not penalize for ties on Y. Frank
Tyler Rinker wrote:
Hello R Community, I'm continuing to work through logistic regression (thanks for all the help on score test) and have come up against a new opposition. I'm trying to compute Somers Dyx as some suggest this is the preferred method to Somers Dxy (Demaris, 1992). I have searchered the [R] archieves to no avail for a function or code to compute Dyx (not Dxy). The overview of Hmisc has mention of Dyx for the rcorr.cens function but this appears to be a misprint because the manual states the function finds Dxy. Peng and So (1998) state that the Dyx is easily calculated in SAS (which tells me the same is possible for [R]). Yang, K., Miller, G. J., & Miller, G. state that: (Tau-b)^2=Somers Dxy * Somers Dyx
so maybe an approach would be to write a function that is:
Somers Dyx<-(Tau-b)^2/Somers Dxy I just don't want to waste time if this is incorrect logic and/or there's an easier way to calculate this thing; perhaps there?s a ?golden? function already created in an [R] package that I'm overlooking. Thanks in advance, Tyler [[alternative HTML version deleted]]
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----- Frank Harrell Department of Biostatistics, Vanderbilt University -- View this message in context: http://r.789695.n4.nabble.com/Somers-Dyx-tp3593119p3593649.html Sent from the R help mailing list archive at Nabble.com.