[R] basehaz error?

Powers, Daniel A dpowers at austin.utexas.edu
Mon Nov 24 17:35:32 CET 2008


R-users--

I am wondering if the cumulative hazard is being correctly computed when evaluated using centered=FALSE. In the bazehaz code (from the survival package) (below), I think  

H <- H * exp(-bz0)  should be 
H <- H * exp(bz0)

 function (fit, centered = TRUE) 
{
    if (!inherits(fit, "coxph")) 
        stop("must be a coxph object")
    sfit <- survfit(fit)
    H <- -log(sfit$surv)
    strata <- sfit$strata
    if (!is.null(strata)) 
        strata <- rep(names(strata), strata)
    if (!centered) {
        z0 <- fit$means
        bz0 <- sum(z0 * coef(fit))
        H <- H * exp(-bz0)
    }
    if (is.null(strata)) 
        return(data.frame(hazard = H, time = sfit$time))
    else return(data.frame(hazard = H, time = sfit$time, strata = strata))
}

Thanks,
Dan



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