R help - Sep 2006 - Step procedure and Akaike information criterion

Please can you help me
I have the following problem:
I have selected an lm model through the step procedure which visualize for each
step the AIC value; then I have calculated for the initial model and the
selected one the AIC using the funnction AIC. The results are
different.What's happened?

Emilia Rocco
Dipartimento di Statistica  "G. Parenti"
Università di Firenze
e-mail: rocco@ds.unifi.it

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compare ?AIC with ?extractAIC, which explains the difference.

On 20/09/06, Emilia Rocco <rocco at ds.unifi.it>
wrote:
> Please can you help me
> I have the following problem:
> I have selected an lm model through the step procedure which visualize for
each step the AIC value; then I have calculated for the initial model and the
selected one the AIC using the funnction AIC. The results are
different.What's happened?
>
> Emilia Rocco
> Dipartimento di Statistica  "G. Parenti"
> Universit? di Firenze
> e-mail: rocco at ds.unifi.it
>
>         [[alternative HTML version deleted]]
>
>
>
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
>

-- 
================================David Barron
Said Business School
University of Oxford
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