Re: [R] AOV with repeated measures

From: Michael Jerosch-Herold <jeroschh_at_ohsu.edu>
Date: Fri 28 Oct 2005 - 06:51:50 EST


You probably need specify the repeated measures by using an "Error" term in aov for repeated measures:

aov(trait ~ species + strain + Error(species/strain))

Take a look at Ripley's book.

Treat above with caution: I am no expert, but the answer is in that direction...

Michael Jerosch-Herold

I have a question on using R to analyze data with repeated measurements. I have 2 species with several strains (12) per species, each of which has been measured twice with for a given trait. No particular covariance, just two measures. Now I want to analyze the data with an ANOVA (aov) considering these repeated measures to get the MSq and SSq for the species and strain level. I would like to know how to write the ANOVA model in R. I have done the following:

aov(trait ~ species + strain/replicate)

Is it accurate?

Thanks a lot,

Christian



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