R: Examples for 'survival::survreg.distributions'

### ** Examples

# time transformation
survreg(Surv(time, status) ~ ph.ecog + sex, dist='weibull', data=lung)

Call:
survreg(formula = Surv(time, status) ~ ph.ecog + sex, data = lung, 
    dist = "weibull")

Coefficients:
(Intercept)     ph.ecog         sex 
  5.8195907  -0.3557319   0.4013684 

Scale= 0.7310495 

Loglik(model)= -1133.1   Loglik(intercept only)= -1147.4
	Chisq= 28.73 on 2 degrees of freedom, p= 5.76e-07 
n=227 (1 observation deleted due to missingness)

# change the transformation to work in years
# intercept changes by log(365), everything else stays the same
my.weibull <- survreg.distributions$weibull
my.weibull$trans <- function(y) log(y/365)
my.weibull$itrans <- function(y) 365*exp(y)
survreg(Surv(time, status) ~ ph.ecog + sex, lung, dist=my.weibull)

Call:
survreg(formula = Surv(time, status) ~ ph.ecog + sex, data = lung, 
    dist = my.weibull)

Coefficients:
(Intercept)     ph.ecog         sex 
-0.08030664 -0.35573188  0.40136844 

Scale= 0.7310495 

Loglik(model)= -1133.1   Loglik(intercept only)= -1147.4
	Chisq= 28.73 on 2 degrees of freedom, p= 5.76e-07 
n=227 (1 observation deleted due to missingness)

# Weibull parametrisation
y<-rweibull(1000, shape=2, scale=5)
survreg(Surv(y)~1, dist="weibull")

Call:
survreg(formula = Surv(y) ~ 1, dist = "weibull")

Coefficients:
(Intercept) 
   1.607703 

Scale= 0.4994601 

Loglik(model)= -2201.6   Loglik(intercept only)= -2201.6
n= 1000

# survreg scale parameter maps to 1/shape, linear predictor to log(scale)

# Cauchy fit
mycauchy <- list(name='Cauchy',
                 init= function(x, weights, ...)
                      c(median(x), mad(x)),
                 density= function(x, parms) {
                      temp <- 1/(1 + x^2)
                      cbind(.5 + atan(x)/pi, .5+ atan(-x)/pi,
                            temp/pi, -2 *x*temp, 2*temp*(4*x^2*temp -1))
                      },
                 quantile= function(p, parms) tan((p-.5)*pi),
                 deviance= function(...) stop('deviance residuals not defined')
                 )
survreg(Surv(log(time), status) ~ ph.ecog + sex, lung, dist=mycauchy)

Call:
survreg(formula = Surv(log(time), status) ~ ph.ecog + sex, data = lung, 
    dist = mycauchy)

Coefficients:
(Intercept)     ph.ecog         sex 
  5.4517240  -0.3979387   0.4692383 

Scale= 0.4788955 

Loglik(model)= -274.6   Loglik(intercept only)= -294.9
	Chisq= 40.75 on 2 degrees of freedom, p= 1.42e-09 
n=227 (1 observation deleted due to missingness)

Examples for 'survival::survreg.distributions'

Parametric Survival Distributions