[R] interpreting Weibull survival regression

[Göran Broström]

On Sun, Jun 26, 2005 at 11:28:04PM +0100, Prof Brian Ripley wrote:
> >Here gamma is the usual gamma function, see ?gamma. (I notice in the R
> >documentation of the Weibull distribution that "E(X) = b Gamma(1+1/a)",
> >which is an error; the G should be g (lowercase).)
> 
> It is not an error.  R's function gamma() is said to implement 
> \eqn{\Gamma}{Gamma}: `see ?gamma'!

I see; it's supposed to be mathematics, not R code (of course, since a
'*' otherwise is missing!). But then the documentation is at least
somewhat inconsistent, because in the variance expression, 'gamma' is used.

> 
> -- 
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595

-- 
Göran Broström                    tel: +46 90 786 5223
Professor and Head
Department of Statistics          fax: +46 90 786 6614
Umeå University                   http://www.stat.umu.se/~goran.brostrom/
SE-90187 Umeå, Sweden             e-mail: gb at stat.umu.se