From: Frank E Harrell Jr <f.harrell_at_vanderbilt.edu>

Date: Sat 08 Jul 2006 - 12:21:48 EST

*>
*

*>
*

> I do not need a accelerated failure model, but a

*> proportional hazard model with a f0= weibull,
*

*> exponential, loglogistic or lognormal baseline
*

*> distribution. The hazard function is
*

*> lambda(t)=exp(Xi*beta)*lambda0(t),
*

*> where lambda0 is the baseline hazard
*

*> lambda0(t)=f0(t)/(1-F0(t)) where f0 and F0 are the
*

*> baseline density and cumulative distribution
*

*> functions.
*

*> This is a proportional hazard model since the ratio
*

*> lambda(t|Xi)/lambda(t|Xj)=exp(Xi*beta)/exp(Xj*beta)
*

*> does not depend on t.
*

*>
*

*> Valentin
*

Date: Sat 08 Jul 2006 - 12:21:48 EST

Valentin Dimitrov wrote:

*>
*

>> Those are not proportional hazards families of >> distributions. That is, if >> the distribution is gaussian for one value of the >> hazard ratio parameters >> it will not be gaussian for any other value. >> >> You can get accelerated failure models with these >> distributions using >> survreg() in the survival package. >> >> >> -thomas

> I do not need a accelerated failure model, but a

-- Frank E Harrell Jr Professor and Chair School of Medicine Department of Biostatistics Vanderbilt University ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.htmlReceived on Sat Jul 08 12:21:05 2006

Archive maintained by Robert King, hosted by
the discipline of
statistics at the
University of Newcastle,
Australia.

Archive generated by hypermail 2.1.8, at Sun 09 Jul 2006 - 00:15:57 EST.

*
Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help.
Please read the posting
guide before posting to the list.
*