Re: [R] Compare effects between lm-models

From: Rense Nieuwenhuis <r.nieuwenhuis_at_student.ru.nl>
Date: Mon 22 Jan 2007 - 16:36:02 GMT

Thank you Alain and Max for your swift responses.

  It might be that I'm misunderstanding your responses, but aren't you testing if there is a difference between the two full models? What I want to know, os whether the effect of a specific predictor (x) differs between model1 and model2. I'm not interested (presently) if the fit of model 2 is better than that of model 1 (for instance).

thanks again,

Rense

On Jan 22, 2007, at 16:26 , Kuhn, Max wrote:

> You can use the anova function a la:
>
>> anova(model1, model2)
> Analysis of Variance Table
>
> Model 1: y ~ x
> Model 2: y ~ x + z
> Res.Df RSS Df Sum of Sq F Pr(>F)
> 1 13 4.4947
> 2 12 4.4228 1 0.0720 0.1952 0.6665
>
> I would suggest getting a copy of MASS and/or reading
>
> http://www.stats.ox.ac.uk/pub/MASS3/Exegeses.pdf
>
>
> Max
>
>
>
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