[R] Negative binomial parameterisation in mgcv
s.wood at bath.ac.uk
Wed Nov 13 17:20:36 CET 2013
var(y) = mu + mu^2/theta where E(y) = mu.
On 13/11/13 10:38, 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?
> Best wishes,
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Simon Wood, Mathematical Science, University of Bath BA2 7AY UK
+44 (0)1225 386603 http://people.bath.ac.uk/sw283
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