[R-sig-ME] logistic model with exponential decay
David.Duffy at qimr.edu.au
Sun Dec 21 22:35:31 CET 2008
On Sun, 21 Dec 2008, Stijn Ruiter wrote:
> Thanks David, I should look into that, but I usually estimate discrete-time
> models which are basically logistic regression models on person-years files
> with only the records included that are "at risk". Anyway, do these packages
> also allow for nonlinear effects the way I need them?
Well, your setup is pretty similar to "standard" bivariate survival
problems, with your "nonlinear term" being simply time since the first
event (the father's offence) -- there is a correlation between years at
risk of the index person and years since his/her father offended. Your
assumption of an exponential decay is going to induce a particular
survivor curve. That is, if you included number of years between the
paternal offence and birth of the index person as a
non-time-varying covariate, and instead changed the survival model from a
non-proportional-hazards to say an accelerated failure time model, you may
model the results just as well.
My $0.02, 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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