On Dec 4, 2013, at 7:49 AM, kevinod wrote:
> I have a concern about the survAUC package option AUC.cd.
>
So shouldn't you be sending this to the package authors? They may or may not be
regular readers of R help. It's apackage I have never heard of.
> I am exploring package functionality, specifically AUC statistics for Cox
> Regression, for a small academic project
>
> When utilizing this package on the ovarian data set within that package I
> obtain an AUC statistic of 0.3322928. When AUC calculations use a
> dichotomous outcome such as this, see included R code, the result should lie
> between 0.5 and 1, not 0.33.
>
> Please explain this, I am not certain that the algorithm that is being
> utilized for this package is correct.
>
> Thank you
>
> Kevin O’Donnell, MS Work Environment, MS Env Eng., MS Const Project Mgmt
> Graduate Student
> Department of Biostatistics
> Boston University School of Public Health
> 715 Albany Street Boston, MA
>
> 617-480-1677
>
> x11(h=8,w=11)
> fit = survfit(Surv(futime,fustat) ~ rx)
> plot(fit, mark.time=FALSE, xscale=365.25,main="Plot of Survival Curves by
> Prescription Status",
> xlab='Length of Survival', ylab='Proportion of Individuals who have
> Survived')
> lines(fit[1], lwd=3,lty=2:3, xscale=365.24,col=2)
> lines(fit[2], lwd=2,lty=2:2, xscale=365.24,col=3)
> legend(.2,.2, c("No treatment", "treatment"), lwd=3,lty = 2:3)
>
>
> TR2 = ovarian[1:16,]
> TE2 = ovarian[17:26,]
> train.fit2 = coxph(Surv(futime, fustat) ~ rx,
> x=TRUE, y=TRUE, method="efron", data=TR)
> lp2 = predict(train.fit)
> lpnew2 = predict(train.fit2, newdata=TE2)
> Surv.rsp2 = Surv(TR2$futime, TR2$fustat)
> Surv.rsp.new2 = Surv(TE2$futime, TE2$fustat)
> times2 = seq(10, 1000, 10)
>
> AUC_CD2 = AUC.cd(Surv.rsp2, Surv.rsp.new2, lp2, lpnew2, times2)
>
>
> AUC_hc2 = AUC.hc(Surv.rsp2, Surv.rsp.new2, lpnew2, times2)
>
>
> AUC_sh2 = AUC.sh(Surv.rsp2, Surv.rsp.new2, lp2, lpnew2, times2)
>
>
> AUC_Uno2 = AUC.uno(Surv.rsp2, Surv.rsp.new2, lpnew2, times2)
>
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/R-survAUC-Package-tp4681638.html
> Sent from the R help mailing list archive at Nabble.com.
>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA
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