coxphERR {clinfun}

Heller Explained Relative Risk

Description

Calculates the contribution of a subset of covariates to the explained relative risk derived from the full Cox proportional hazards model.

Usage

  coxphERR(phfit, ngamma=NULL)

Arguments

phfit

The output from a proportional hazards fit.

ngamma

A vector of indices corresponding to covariates of interest. If missing (default), the explained relative risk is computed for the full model.

Details

The object phfit should be the result of a call to coxph with the option x=TRUE.

Value

The function coxphERR returns the vector (ERR, se.ERR). The first component ERR represents the contribution of a subset of covariates to the explained relative risk estimate of the full model. If a set of covariates is not provided, then it computes the estimate of the full model. The second component se.ERR is the standard error of the estimate.

References

Heller G. (2012) A measure of explained risk in the proportional hazards model. Biostatistics

Examples

## Not run: 
 library(survival)
 ovarianfit <- coxph(Surv(futime, fustat) ~ age + resid.ds + rx +
                                           ecog.ps, data=ovarian,x=T) 
 # Compute the explained relative risk (ERR) and
 # its standard error (se.ERR) for the full model.
 coxphERR(ovarianfit)       
 # Compute the contribution of age and ECOG performance status to
 # the explained relative risk. Age and ECOG performance status are 
 # the first and fourth covariates in the model.
 coxphERR(ovarianfit, c(1,4))

## End(Not run)