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 This has been superseded by a subscripting method; see the example below.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 2.38-3 Index]