compareC {compareC} R Documentation

## Testing the difference between two correlated overall C indices

### Description

This is a function used to test if the difference in two correlated overall C indices is statistically significant

### Usage

	compareC(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 or score Y, one for each of the same observations scoreZ The vector of the second measured biomarker or score Z, one for each of the same observations

### Value

 est.c The estimated two C indices est.diff_c The estimated difference of the two C indices, i.e.,C_{XY}-C_{XZ} 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 zscore Z score (test statistic) for hypothesis testing pval P value for the comparison of two C indices

### Note

Under non-random censoring, the returned p-value is statistically invalid as the assumption of random censoring is violated.

### 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,vardiffC
demo(testC)