iauc.comp {survcomp} | R Documentation

## Function to compare two IAUCs through time-dependent ROC curves

### Description

This function compares two integrated areas under the curves (IAUC) through the results of time-dependent ROC curves at some points in time. The statistical test is a Wilcoxon rank sum test for dependent samples.

### Usage

    iauc.comp(auc1, auc2, time)

### Arguments

`auc1` | vector of AUCs computed from the first time-dependent ROC curves for some points in time
`auc2` | vector of AUCs computed from the second time-dependent ROC curves for some points in time
`time` | vector of points in time for which the AUCs are computed

### Details

The two vectors of AUCs must be computed from the same samples (and corresponding survival data) and for the same points in time. The function uses a Wilcoxon rank sum test for dependent samples.

### Value

`p.value` | p-value from the Wilcoxon rank sum test for the comparison iauc1 > iauc2
`iauc1` | value of the IAUC for the first set of time-depdent ROC curves
`iauc2` | value of the IAUC for the second set of time-depdent ROC curves

### Author(s)

Benjamin Haibe-Kains

### References

Wilcoxon, F. (1945) "Individual comparisons by ranking methods", Biometrics Bulletin, 1, pages 80–83.

Haibe-Kains, B. and Desmedt, C. and Sotiriou, C. and Bontempi, G. (2008) "A comparative study of survival models for breast cancer prognostication based on microarray data: does a single gene beat them all?", Bioinformatics, 24, 19, pages 2200–2208.

### See Also

`tdrocc`, `wilcox.test`

### Examples

    set.seed(12345)
    age <- rnorm(30, 50, 10)
    size <- rexp(30,1)
    stime <- rexp(30)
    cens <- runif(30,.5,2)
    sevent <- as.numeric(stime <= cens)
    stime <- pmin(stime, cens)
    ##time-dependent ROC curves
    tt <- unique(sort(stime[sevent == 1]))
    ##size
    mytdroc1 <- NULL
    for(i in 1:length(tt)) {
    	rr <- tdrocc(x=size, surv.time=stime, surv.event=sevent, time=tt[i],
        na.rm=TRUE, verbose=FALSE)
    	mytdroc1 <- c(mytdroc1, list(rr))
    }
    auc1 <- unlist(lapply(mytdroc1, function(x) { return(x$AUC) }))
    ##age
    mytdroc2 <- NULL
    for(i in 1:length(tt)) {
    	rr <- tdrocc(x=age, surv.time=stime, surv.event=sevent, time=tt[i],
        na.rm=TRUE, verbose=FALSE)
    	mytdroc2 <- c(mytdroc2, list(rr))
    }
    auc2 <- unlist(lapply(mytdroc2, function(x) { return(x$AUC) }))
    iauc.comp(auc1=auc1, auc2=auc2, time=tt)

[Package survcomp version 1.44.1 Index]