Re: [R] what does the S.D. returned by {Hmisc} rcorr.cens measure?

Thanks for your reply Prof Harrell!! Could you kindly list some references of the fomula for calculating the SD of Somer's D in this kind of application? Because I couldnt find any.. -- View this message in context:

[R] which does the S.D. returned by {Hmisc} rcorr.cens measure?

Dear R-help, This is an example in the {Hmisc} manual under rcorr.cens function: set.seed(1) x - round(rnorm(200)) y - rnorm(200) round(rcorr.cens(x, y, outx=F),4) C IndexDxy S.D. nmissing uncensored Relevant Pairs Concordant

Re: [R] Interpreting the example given by Prof Frank Harrell in {Design} validate.cph

Thank you very very very much Prof Harrell!! You've made my day!! -- View this message in context: http://r.789695.n4.nabble.com/Interpreting-the-example-given-by-Prof-Frank-Harrell-in-Design-validate-cph-tp3316820p3325844.html Sent from the R help mailing list archive at Nabble.com.

Re: [R] Interpreting the example given by Prof Frank Harrell in {Design} validate.cph

Dear Prof Frank, I tried to simulate an example data set as close as possible to my own real data with the codes below. There are only two covariates, tumor(3 levels) and ecog(3 levels). rx is treatment (4 levels). Validation with the stratified model (by rx) had a negative R2.. and the R2 under

Re: [R] Interpreting the example given by Prof Frank Harrell in {Design} validate.cph

I really appreciate your help Prof Harrell! I followed your instruction and re-ran the second model without strat but with surv=TRUE, time.inc=30, and u=30 to validate, the Dxy was really the same as that in the first model output! But this confused me...shouldn't the Dxy be positive in this

[R] Interpreting the example given by Prof Frank Harrell in {Design} validate.cph

Dear R-help, I am having a problem with the interpretation of result from validate.cph in the Design package. My purpose is to fit a cox model and validate the Somer's Dxy. I used the hypothetical data given in the help manual with modification to the cox model fit. My research problem is very

Re: [R] Interpreting the example given by Prof Frank Harrell in {Design} validate.cph

Thank you very much Prof Harrell! Sorry that I am new to this forum, and so ain't familiar with how to post message appropriately. I repeated the same procedure using a dataset from the {survival} package. This time I used the {rms} package, and 100 bootstrap samples: library(rms)

[R] contrasting Somer's D from Design package

Dear R help, I am having a problem with the Design package and my problem is detailed here. I fit a cox model to my data and validate the Somer's Dxy using the Design package. (Because of computation time problem, i only try 10 bootstrap samples for the time being) This is the model without