# cox.zph

From survival v2.11-4
by Thomas Lumley

##### Test the Proportional Hazards Assumption of a Cox Regression

Test the proportional hazards assumption for a Cox regression model fit
(`coxph`

).

- Keywords
- survival

##### Usage

`cox.zph(fit, transform="km", global=TRUE)`

##### Arguments

- fit
- the result of fitting a Cox regression model, using the
`coxph`

function. - transform
- a character string specifying how the survival times should be transformed
before the test is performed.
Possible values are
`"km"`

,`"rank"`

,`"identity"`

or a function of one argument. - global
- should a global chi-square test be done, in addition to the per-variable tests.

##### Value

- an object of class
`"cox.zph"`

, with components:

##### Note

The `plot`

method requires the `splines`

library

##### item

- table
- x
- y
- call

##### code

`slope=0`

##### References

P. Grambsch and T. Therneau (1994),
Proportional hazards tests and diagnostics based on weighted residuals.
*Biometrika,*
**81**, 515-26.

##### See Also

##### Examples

```
data(ovarian)
fit <- coxph( Surv(futime, fustat) ~ age + rx, ovarian)
temp<- cox.zph(fit)
print(temp) #display the results
plot(temp) #plot curves
```

*Documentation reproduced from package survival, version 2.11-4, License: GPL2*

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