R: Graphical Test of Proportional Hazards

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,
            xlab="Time", ylab, lty=1:2, col=1, lwd=1, ...)

### 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 to use for the lines
`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 This has been superseded by a subscripting method; see the example below.
`xlab` | label for the x-axis of the plot
`ylab` | optional label for the y-axis of the plot. If missing a default label is provided. This can be a vector of labels.
`lty, col, lwd` | line type, color, and line width for the overlaid curve. Each of these can be vector of length 2, in which case the second element is used for the confidence interval.
`...` | 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=3)      # Look at Karnofsy score, old way of doing plot
    plot(temp[3])     # New way with subscripting
    abline(0, 0, lty=3)
    # Add the linear fit as well
    abline(lm(temp$y[,3] ~ temp$x)$coefficients, lty=4, col=3)
    title(main="VA Lung Study")

[Package survival version 3.2-7 Index]