[R] question about nlme...

[Dieter Menne]

Jeff Harring wrote:
> 
> I am looking for R code to be able to fit a linear-linear piecewise 
> model with person-specific changepoint. I have searched the web, but 
> have not been able to locate any code.
> 
> ..
> I would appreciate any advice on this code or guidance as to where to 
> search for example code to fit this nonlinear mixed effects model.
> 
> 

I had good success in fitting piecewise functions with continuous
derivatives, e.g. a logistic function with a linear continuation. Things did
not work well with nlme when there was a discontinuity. There is an
discussion from 2000 right from Douglas Bates' and Mary Lindstrom's mouth
for nls and the hockey-stick, so it could be possible to get is to work with
good data.

http://www.biostat.wustl.edu/archives/html/s-news/2000-04/msg00209.html

Also check

http://markmail.org/message/6p63i4cxfk6enlp5

Dieter


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