[R] retrieving coefficients from nls() when it fails to converge
Potter, David M
david_m_potter at groton.pfizer.com
Thu Oct 16 17:55:29 CEST 2003
Hi --
I am fitting four-parameter logistic regression models using nls(),
typically within the body of a loop. Sometimes a fit fails to converge and
yet I would like to pull off the coefficients from the last iteration and
use them to compute backfitted (i.e., inverse prediction) values.
Note: To ignore the fit completely, but have the loop continue, I have
successfully used try(), but in this case the fits are sufficient for
getting backfitted values (even though the coefficients are poorly
estimated), so I need the actual coefficients.
R information:
platform i386-pc-mingw32
arch i386
os mingw32
system i386, mingw32
status
major 1
minor 7.1
year 2003
month 06
day 16
language R
Thanks for your help.
David
__
David M. Potter
Groton Nonclinical Statistics
Pfizer Global Research and Development
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