glm model syntax

N+M gives only the main effects, N:M gives only the interaction, and G*M gives the main effects and the interaction.
-----Original Message-----
From: r-help-bounces at r-project.org 
[mailto:r-help-bounces at r-project.org] On Behalf Of Birgit Lemcke
Sent: Friday, May 16, 2008 11:27 AM
To: R Hilfe
Subject: [R] glm model syntax

Hello R users!

What is the difference between

glm(A~N+M)
glm(A~N:M)
glm(A~N*M)

Thanks in advance.

Birgit

Birgit Lemcke
Institut f?r Systematische Botanik
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birgit.lemcke at systbot.uzh.ch

175 Jahre UZH
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glm model syntax

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