[R] Individual log likelihoods of nlsList objects.

Ken Kelley kkelley at nd.edu
Thu Jul 1 21:23:16 CEST 2004

Hello all.

I was wondering if the logLike.nls() and logLike.nlme() functions are still
being used. Neither function seems to be available in the most recent
release of R (1.9.1). The following is contained in the help file for
logLik(): "classes which already have methods for this function include:
'glm', 'lm', 'nls' and 'gls', 'lme' and others in package 'nlme'." Thus, I
was expecting that logLik.nls() and logLik.nlme() could be used for objects
of the nls and nlme class, respectively. Are these functions no longer
needed because logLike() subsumes logLike.nls() and logLike.nlme() as
special cases? Did/does logLike.nls() and logLike.nlme() have any advantages
above and beyond logLike() when applying them to nls and nlme objects? 

On a related note, is there a way to get the log likelihoods of each
individual from an nlsList object? 

On p. 349 of Pinheiro and Bates (2000) the logLik() function is said to give
the sum of the individual nls log-likelihoods. However,
logLike(some.nlsList.object) does not work for me (even when there are no
NAs). Any ideas?

Thanks for any thoughts or feedback. Have a good day,

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