[R] Negative binomial parameterisation in mgcv

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Nov 13 10:54:21 CET 2013

On 13/11/2013 09:38, Mark Payne wrote:
> Dear R-help,
> The negative binomial distribution has several different
> parameterisations, but I can't seem to figure out what the exact one
> used in mgcv's negbin family is? negbin() requires a theta argument,
> but its not clear anywhere in the documentation (that I can find), how
> this parameter should be interpreted - for example, can it be less
> than 1?

I believe it is the same as MASS (the package) explained in MASS (the 
book).  As its help says ....

> Best wishes,
> MArk

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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