On Wed, Jun 08, 2005 at 08:39:21PM -0400, [EMAIL PROTECTED] wrote: > I was wondering if someone familiar > with survival analysis can help me with > the following. > I would like to fit a Weibull curve, > that may be dependent on a covariate, > my dataframe "labdata" that has the > fields "cov", "time", and "censor". Do > I do the following? > wieb<-survreg(Surv(labdata$time, > labadata$censor)~labdata$cov, > dist="weibull") > > This returns: > >weib > Call: > survreg(formula = Surv(labdata$time, > labdata$censor) ~ labdata$cov, > dist = "weibull") > > Coefficients: > (Intercept) labdata$cov > 8.091955112 0.001552897 > > Scale= 0.7532474 > > Loglik(model)= -12633.6 > Loglik(intercept only)= -12734.8 > Chisq= 202.41 on 1 degrees of > freedom, p= 0 > n= 5496 > > > I am not quite sure how to use the > output. I see that it gives the Scale > parameter. How do I find the Shape > paramater as a function of the > covariate?
You don't. The analysis is performed on the logs of durations, so scale is transformed to location and shape to scale. For more intuitive output, use 'weibreg' in package 'eha'. It can also handle left truncated data. But only Weibull (and exponential) regression. > > Thank you, > Steven > > --------------------------------------- > ------------------------- > Steven Shechter > PhD Candidate in Industrial Engineering > University of Pittsburgh > www.pitt.edu/~sms13 > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > -- G�ran Brostr�m tel: +46 90 786 5223 Professor and Head Department of Statistics fax: +46 90 786 6614 Ume� University http://www.stat.umu.se/~goran.brostrom/ SE-90187 Ume�, Sweden e-mail: [EMAIL PROTECTED] ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
