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\name{plot.cox.zph}
\alias{plot.cox.zph}
\title{
Graphical Test of Proportional Hazards
}
\description{
Displays a graph of the scaled Schoenfeld residuals, along with a smooth curve.
}
\usage{
\method{plot}{cox.zph}(x, resid=TRUE, se=TRUE, df=4, nsmo=40, var, \dots)
}
\arguments{
\item{x}{
result of the \code{cox.zph} function.
}
\item{resid}{
a logical value, if \code{TRUE} the residuals are included on the plot, as well as the smooth fit.
}
\item{se}{
a logical value, if \code{TRUE}, confidence bands at two standard errors
will be added.
}
\item{df}{
the degrees of freedom for the fitted natural spline, \code{df=2} leads
to a linear fit.
}
\item{nsmo}{
number of points used to plot the fitted spline.
}
\item{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This has been superseded by a subscripting method; see the example below.
}
\item{\dots}{
additional graphical arguments passed to the \code{plot} function.
}
}
\section{Side Effects}{
a plot is produced on the current graphics device.
}
\seealso{
\code{\link{coxph}}, \code{\link{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")
}
\keyword{survival}
|
