[R-sig-ME] revised link function of logistic regression model?
davidD at qimr.edu.au
Fri Jun 24 09:20:38 CEST 2011
On Thu, 23 Jun 2011, Jian Zhang wrote:
> My question is: If I changed the function of the survival probability to
> the following: P(y=1|x) = (exp(b0+b1*x) / (1+exp(b0+b1*x)) ) ^t, how
> should I do the regression using the glm? How can I add the "t" into the
> function as a predictor variable? Or should I revise the link function?
I shall hazard a guess and say that you can't, exactly as you have
specified it. You could fit such a model by ML, but you would have to
hand code it using nlme (?) or directly maximizing the likelihood using
optim() etc. But I suspect there are many similar models that might be
better behaved. Are you trying to fit a parametric survival model in a
Cheers, David Duffy.
| David Duffy (MBBS PhD) ,-_|\
| email: davidD at qimr.edu.au ph: INT+61+7+3362-0217 fax: -0101 / *
| Epidemiology Unit, Queensland Institute of Medical Research \_,-._/
| 300 Herston Rd, Brisbane, Queensland 4029, Australia GPG 4D0B994A v
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