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using rcorr.cens for Goodman Kruskal gamma
2 messages · Colin Robertson, Frank E Harrell Jr
Colin Robertson wrote:
Dear List, I would like to calculate the Goodman-Kruskal gamma for the predicted classes obtained from an ordinal regression model using lrm in the Design package. I couldn't find a way to get gamma for predicted values in Design so have found previous positings suggesting to use : Rcorr.cens(x, S outx = TRUE) in the Hmisc package My question is, will this work for predicted vs observed factors? I.e. x = predicted class and S = observed class? Or is there a better way to obtain this? I used the maximum individual probability for each observation to determine the predicted class.
Rank correlation measures are for correlating a continuous or ordinal prediction with a response (continuous, ordinal, or binary). So you should be able to do something like rcorr.cens(predict(fit), as.numeric(Y), outx=TRUE). Note that rcorr is all lower case. This assumes that the levels of Y are in order, as does lrm. Note that the new version of lrm has a method for getting predicted mean scores from an ordinal lrm. Frank
Any help appreciated, Thanks Colin Colin Robertson Dept of Geography University of Victoria
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University