[Rd] How do I know if the deviance of a glm fit was fixed?
Prof Brian Ripley
Fri, 18 Jan 2002 17:26:01 +0000 (GMT)
On Fri, 18 Jan 2002, Duncan Murdoch wrote:
> I'm writing functions that need to behave differently for
> GLMs like binomial and Poisson with fixed deviance, and those like
> normal or gamma or quasi where the deviance is estimated from the
> data. Given a glm object, is there a simple way to tell this
> directly, or do I have to look at the name of the family?
Did you mean dispersion fixed?
S/R do not take the dispersion into account: it is not in the fit.
It is used by the summary, predict and anova methods (and that's all as I
recall). And they do look at the family name.
Brian D. Ripley, firstname.lastname@example.org
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
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