survPHplot {biostat3}

R Documentation

Plot to assess non-proportionality

Description

Plot of log(time) versus -log(-log(survival)) to assess non-proportionality. A constant distance between curves suggest proportionality.

Usage

survPHplot(formula, data, subset, contrasts, weights, col = 1:5,
           lty = 1:5, pch = 19, xlab = "Time (log scale)",
           ylab = "-log(-log(Survival))", log = "x",
           legend.args = list(), ...)

Arguments

formula	either (i) formula with a Surv object on the left-hand-side and stratification covariates on the right-hand-side, or (ii) a survfit object
data	data argument passed to survfit
subset	subset argument passed to survfit
contrasts	contrasts argument passed to survfit
weights	weights argument passed to survfit
col	colours of the curves passed to lines
lty	line type of the curves passed to lines
pch	pch for the curves passed to points
xlab	xlab graphics argument passed to plot.default
ylab	ylab graphics argument passed to plot.default
log	log graphics argument passed to plot.default
legend.args	list of arguments passed to legend. These arguments update the base arguments, which are list(x="topright",legend=names(survfit$strata),col=col,lty=lty,pch=pch)
...	Other arguments passed to plot.default

Details

The default plot is to use straight lines between the transformed survival values for each strata, rather than using steps.

Value

Primary purpose is for plotting (side effect). The return value is initial plot.

Examples

survPHplot(Surv(surv_mm/12, status == "Dead: cancer") ~ year8594,
           data=colon, subset=(stage=="Localised"),
           legend.args=list(bty="n"))

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