Hi Patrick,
there exist specialized functionality in R that offer both automated
calculation of
starting values and relatively robust optimization, which can be used with
success in many
common cases of nonlinear regression, also for your data:
library(drc) # on CRAN
## Fitting 3-parameter lo
Patrick Giraudoux univ-fcomte.fr> writes:
>
> Patrick Burns a écrit :
> > Patrick Giraudoux wrote:
> >> Bert Gunter a écrit :
> >>> Based on a simple scatterplot of pourcma vs transat, a 4 parameter
> >>> logistic
> >>> looks like wild overfitting, and that may be the source of your
> >>> pro
Patrick Burns a écrit :
Patrick Giraudoux wrote:
Bert Gunter a écrit :
Based on a simple scatterplot of pourcma vs transat, a 4 parameter
logistic
looks like wild overfitting, and that may be the source of your
problems.
Given the huge scatter, a straight line is about as much as would seem
Patrick Giraudoux wrote:
Bert Gunter a écrit :
Based on a simple scatterplot of pourcma vs transat, a 4 parameter
logistic
looks like wild overfitting, and that may be the source of your
problems.
Given the huge scatter, a straight line is about as much as would seem
sensible. I think this fa
Bert Gunter a écrit :
Based on a simple scatterplot of pourcma vs transat, a 4 parameter logistic
looks like wild overfitting, and that may be the source of your problems.
Given the huge scatter, a straight line is about as much as would seem
sensible. I think this falls into the "Why ever would
c: Francis Raoul
Subject: [R] nls, convergence and starting values
"in non linear modelling finding appropriate starting values is
something like an art"... (maybe from somewhere in Crawley , 2007) Here
a colleague and I just want to compare different response models to a
null model. Th
"in non linear modelling finding appropriate starting values is
something like an art"... (maybe from somewhere in Crawley , 2007) Here
a colleague and I just want to compare different response models to a
null model. This has worked OK for almost all the other data sets except
that one (dumped b
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