binomial(link="inverse")
On Wed, 10 Sep 2008, Thomas Lumley wrote:
On Wed, 10 Sep 2008, Prof Brian Ripley wrote:
As to why the list of links known by name is as it is, that seems history. in part the White Book history of S. I've always thought it an error that 'log' was a standard link for binomial, as the range does not match the specification of probabilities (and S did not do so, MASS Table 7.1 ).
I think I added binomial("log"): log-binomial regression is quite popular and
useful in epidemiology (where effect sizes are small enough that keeping away
from the boundary may be less of a problem than people's inability to
understand odds ratios).
Yes. My comment was about being "standard" and so easy to use unthinkingly. Where a Poisson approximation to the binomial would be good, a log link is also going to be appropriate. Had we then the infrastructure in place we have now, I would have been suggesting (like identity) that it be available via an (easy) user extension.
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