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This has been superseded by a subscripting method; see the example below.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 graphical arguments passed to the plot function.

Side Effects

a plot is produced on the current graphics device.

See Also

coxph, cox.zph.

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 2.36-14 Index]