[R-sig-phylo] fitContinuous in geiger: positive log-likelihoods when trait values <1

Nick Matzke matzke at berkeley.edu
Mon Mar 7 21:37:48 CET 2011

Hi all,

It seems to be a popular week for questions!

I am running fitContinuous on a variety of continuous trait 
data.  I am noticing that when the traits are in units where 
the max is less than 1 (these are not ratio data, though), 
many of the various models produce log-likelihoods that are 
positive, which ought to be impossible.

If I rescale the trait values, e.g. by multiplying them by 
100, the problem goes away and all log-likelihoods are 
negative, and come out somewhat similar to each other 
between the BM, OU, etc. models, as one would expect.

Any hint about why this might be?


Nicholas J. Matzke
Ph.D. Candidate, Graduate Student Researcher

Huelsenbeck Lab
Center for Theoretical Evolutionary Genomics
4151 VLSB (Valley Life Sciences Building)
Department of Integrative Biology
University of California, Berkeley

Graduate Student Instructor, IB200B
Principles of Phylogenetics: Ecology and Evolution

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