hits=-2.6 tests=BAYES_00
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On Fri, 2008-01-25 at 14:21 +0000, David Winsemius wrote:
> "Paul Sweeting" <[EMAIL PROTECTED]> wrote in
> news:[EMAIL PROTECTED]:
<snip />
> The most straightforward approach would be to use glm() with
> family="poisson", a.k.a Poisson regression. Don't ask me why
> Gamma is capitalized as an R family but poisson is not, I don't know.
That is because there already is a gamma() for the *Gamma function*.
>From ?glm:
family: a description of the error distribution and link function to
be used in the model. This can be a character string naming a
family function, a family function or the result of a call to
a family function. (See 'family' for details of family
functions.)
So the character string must match the *name* of the correct family
function, hence you need to use "Gamma" even though you are not calling
the function directly. This isn't a string to simply say which family
you want, it has a slightly deeper meaning, hence the presumed
inconsistency.
I guess gamma() existed before the Gamma family function was included in
R or S, hence it got the lowercase name "gamma".
G
<snip />
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Dr. Gavin Simpson [t] +44 (0)20 7679 0522
ECRC, UCL Geography, [f] +44 (0)20 7679 0565
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