Parametric Proportional Hazards form of AFT Models

Translates an accelerated failure time (AFT) model fitted by psm to proportional hazards form, if the fitted model was a Weibull or exponential model (extreme value distribution with "log" link).

pphsm(fit)
# S3 method for class 'pphsm'
print(x, digits=max(options()$digits - 4, 3),
correlation=TRUE, ...)
# S3 method for class 'pphsm'
vcov(object, ...)

Arguments

fit

fit object created by psm

x

result of psm

digits

how many significant digits are to be used for the returned value

correlation

set to FALSE to suppress printing of correlation matrix of parameter estimates

...

ignored

object

a pphsm object

Value

a new fit object with transformed parameter estimates

Author

Frank Harrell
Department of Biostatistics
Vanderbilt University
fh@fharrell.com

See also

psm, summary.rms, print.pphsm

Examples

require(survival)
set.seed(1)
S <- Surv(runif(100))
x <- runif(100)
dd <- datadist(x); options(datadist='dd')
f <- psm(S ~ x, dist="exponential")
#> Error in Design(m, formula = formula, specials = c("strata", "cluster")): dataset dd not found for options(datadist=)
summary(f)        # effects on log(T) scale
#> Error: object 'f' not found
f.ph <- pphsm(f)
#> Warning: at present, pphsm does not return the correct covariance matrix
#> Error: object 'f' not found
if (FALSE) summary(f.ph)     # effects on hazard ratio scale # \dontrun{}
options(datadist=NULL)