[R] Problem about step and stepAIC

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Apr 27 12:12:46 CEST 2011

On Wed, 27 Apr 2011, Maggie Wong wrote:

> Hello,
> I am now running a multiple linear regression program, but I do not know the
> difference between the command step and stepAIC.

And what is the 'problem about step and stepAIC'?  You can find out by 
reading the help, as the posting guide asked you to do before posting. 
But to remind you, ?step says


      B. D. Ripley: ‘step’ is a slightly simplified version of ‘stepAIC’
      in package ‘MASS’ (Venables & Ripley, 2002 and earlier editions).

      The idea of a ‘step’ function follows that described in Hastie &
      Pregibon (1992); but the implementation in R is more general.

If you really want to know what 'slightly simplified' means you would 
need to specify the 'at a minimum' information the posting guide asked 
you to supply, for it depends on the versions of R and MASS. 
However, the best way to find out is to read the code for yourself: it 
is uniikely that anyone will be prepared to do so for you.

> Thanks.
> Maggie
> 	[[alternative HTML version deleted]]
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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

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