vardiffC {compareC} R Documentation

## Variance estimation of the difference between two correlated overall C indices

### Description

This is a function used to estimate the variance of the difference between two correlated overall C indices

### Usage

	vardiffC(timeX, statusX, scoreY, scoreZ)


### Arguments

 timeX The vector of actual survival time X, one survival time for each observation statusX The matching vector of event indicator for time X, 1 if occured and 0 otherwise scoreY The vector of the first measured biomarker Y, one for each of the same observations, based on which the variance of the difference in overall C indices is to be estimated scoreZ The vector of the second measured biomarker Z, one for each of the same observations, based on which the variance of the difference in overall C indices is to be estimated

### Value

 est.vardiff_c The estimated variance of the difference of two C indices est.varCxy The estimated variance of the C index for scoreY est.varCxz The estimated variance of the C index for scoreZ est.cov The estimated covariance between the two C indices for scoreY and that for scoreZ

### Author(s)

Le Kang, Weijie Chen

### References

Harrell FE, Califf RM, Pryor DB, Lee KL, and Rosati RA. (1982) Evaluating the yield of medical tests. The Journal of the American Medical Association, 247(18), 2543–2546

Pencina MJ and D'Agostino RB. (2004) Overall C as a measure of discrimination in survival analysis: model specific population value and confidence interval estimation. Statistics in Medicine, 23(13), 2109–2123

Kang L, Chen W, Petrick NA, and Gallas BD. (2014) Comparing two correlated C indices with right-censored survival outcome: a one-shot nonparametric approach. Statistics in Medicine, 34(4), 685–703, doi: 10.1002/sim.6370

estC,compareC
demo(testC)