survreg.distributions {survival5} | R Documentation |
survreg.distributions
List of distributions for accelerated failure models. These are location-scale families for some transformation of time. The entry describes the cdf F and density f of a canonical member of the family.
There are two basic formats
name: | name of distribution |
variance: | Variance |
init(x,weights,...): | Function returning an initial |
mean and | variance |
deviance(y,scale,parms): | Function returning the deviance |
density(x,parms): | Function returning F, |
1-F,f,f'/f,f''/f | |
quantile(p,parms): | Quantile function |
scale: | Optional fixed value for scale parameter |
name: | name of distribution |
dist: | name of transformed distribution |
trans: | transformation (eg log) |
dtrans: | derivative of transformation |
itrans: | inverse of transformation |
scale: | Optional fixed value for scale parameter |
There are four basic distributions:extreme
, gaussian
,
logistic
and t
. The last three
are parametrised in the same way as the distributions already present in
R. The extreme value cdf is
F=1-e^{-e^t}.
When the logarithm of survival time has one of the first three distributions
we obtain respectively lognormal
,loglogistic
and
weibull
.
The other predefined distributions are defined in terms of these. The
exponential
and rayleigh
distributions are Weibull
distributions with fixed scale
of 1 and 0.5 respectively, and
loggaussian
is a synonym for lognormal
.
survreg
, pnorm
,
code{plogis}, pt
,
the documentation in doc/survival.ps.gz