[R] estimation of lambda and gamma with std errors for a weibull model

Göran Broström gb at stat.umu.se
Wed Jan 14 22:45:56 CET 2004

On Wed, Jan 14, 2004 at 09:10:51PM +0100, Fredrik Lundgren wrote:
> Dear R experts,
> How should lambda and gamma (with std.errors) be calculated for a weibull model with age as an independent predictor? I have assumed that this can be done with survreg with e. g. (summary(survreg(Surv(time, status) ~ age, dist = 'weibull')) ) and predict.survreg with e.g. (predict(model, se.fit = T,  newdata = data.frame(age = seq(50, 80, 5)) but unfortunately I'm uncapable to sort out how to get the lambda and gamma values (with std.errors). I haven't found any example of this in the help pages and would really appreciate  any help!

In my package 'eha', function 'weibreg', you will find short discussion of the
different parametrizations of the Weibull distribution. Weibull (in base) and
weibreg (eha) use the same parametrization, different from the one in 
survreg. See the help page for weibreg. Oops, I can spot an error in that page;
the reference to 'dgamma' should really be to 'dweibull'.


> With best wishes and thanks in advance for any help
> Fredrik Lundgren
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 Göran Broström                    tel: +46 90 786 5223
 Department of Statistics          fax: +46 90 786 6614
 Umeå University                   http://www.stat.umu.se/egna/gb/
 SE-90187 Umeå, Sweden             e-mail: gb at stat.umu.se

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