R: R2-type coefficients for Cox proportional hazards models

OXS {survAUC} | R Documentation

## R2-type coefficients for Cox proportional hazards models

### Description

R2-type Coefficients for Cox proportional hazards models

### Usage

    OXS(Surv.rsp, lp, lp0)
    Nagelk(Surv.rsp, lp, lp0)
    XO(Surv.rsp, lp, lp0)

### Arguments

`Surv.rsp` | A `Surv(.,.)` object containing to the outcome of the test data.
`lp` | The vector of predictors.
`lp0` | The vector of predictors obtained from the covariate-free null model.

### Details

The `OXS`, `Nagelk` and `XO` functions implement three types of R2 coefficients for right-censored time-to-event data: (a) The coefficient proposed by O'Quigley et al. (2005) (`OXS`), (b) the coefficient proposed by Nagelkerke (1991) (`Nagelk`) and (c) the coefficient proposed by Xu and O'Quigley (1999) (`XO`).

Because the `OXS`, `Nagelk` and `XO` functions assume that `lp` and `lpnew` were derived from a correctly specified Cox proportional hazards model, estimates obtained from these functions are only valid if the Cox model holds.

### Value

The estimated R2 coefficient.

### References

Nagelkerke, N. J. D. (1991).
A note on a general definition of the coefficient of determination.
Biometrika 78, 691–692.

O'Quigley, J., R. Xu, and J. Stare (2005).
Explained randomness in proportional hazards models.
Statistics in Medicine 24, 479–489.

Xu, R. and J. O'Quigley (1999).
A measure of dependence for proportional hazards models.
Journal of Nonparametric Statistics 12, 83–107.

### See Also

`predErr`, `schemper`, `GHCI`

### Examples

    TR <- ovarian[1:16,]
    TE <- ovarian[17:26,]
    train.fit  <- coxph(Surv(futime, fustat) ~ age,
                        x=TRUE, y=TRUE, method="breslow", data=TR)

    model0 <- coxph(Surv(futime, fustat)~1, data=TR)
    model1 <- coxph(Surv(futime, fustat)~age, data=TR)
    f0 <- rep(0,nrow(TE))
    f1 <- predict(model1, newdata=TE)
    Surv.res <- Surv(TE$futime, TE$fustat)

    OXS(Surv.res, f1, f0)
    Nagelk(Surv.res, f1, f0)
    XO(Surv.res, f1, f0)

[Package survAUC version 1.0-5 Index]