plot.cox.zph {survival}R Documentation

Graphical Test of Proportional Hazards

Description

Displays a graph of the scaled Schoenfeld residuals, along with a smooth curve.

Usage

## S3 method for class 'cox.zph':
plot(x, resid=TRUE, se=TRUE, df=4, nsmo=40, var, ...)

Arguments

x result of the cox.zph function.
resid a logical value, if TRUE the residuals are included on the plot, as well as the smooth fit.
se a logical value, if TRUE, confidence bands at two standard errors will be added.
df the degrees of freedom for the fitted natural spline, df=2 leads to a linear fit.
nsmo number of points used to plot the fitted spline.
var the set of variables for which plots are desired. By default, plots are produced in turn for each variable of a model. Selection of a single variable allows other features to be added to the plot, e.g., a horizontal line at zero or a main title.
This has been superseded by a subscripting method; see the example below.
... additional arguments passed to the plot function.

Side Effects

a plot is produced on the current graphics device.

See Also

cox.zph, coxph

Examples

vfit <- coxph(Surv(time,status) ~ trt + factor(celltype) +
              karno + age, data=veteran, x=TRUE)
temp <- cox.zph(vfit)
plot(temp, var=5)      # Look at Karnofsy score, old way of doing plot
plot(temp[5])     # New way with subscripting
abline(0, 0, lty=3)
# Add the linear fit as well 
abline(lm(temp$y[,5] ~ temp$x)$coefficients, lty=4, col=3) 
title(main="VA Lung Study")
[Package survival version 2.20 Index]