compareC {compareC}

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

See Also

estC,vardiffC

Examples

demo(testC)