R help - Jul 2007 - exact AIC

Hi,

I am using the stepAIC function on the MASS package that does model
selection by exact AIC. I'm not sure what the term 'exact AIC'
means,
and how it differs from  AIC.

Thank you,

Selene Zarate

On Tue, 3 Jul 2007, Selene Z?rate wrote:
> I am using the stepAIC function on the MASS package that does model
> selection by exact AIC. I'm not sure what the term 'exact AIC'
means,
> and how it differs from  AIC.
It doesn't, but there are approximations to AIC in use.  This is explained 
in the book stepAIC supports (one is C_p, for example).

-- 
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)
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