[R] Specifying error terms in aov and lme

Nathaniel Street N.R.STREET at soton.ac.uk
Thu Nov 4 13:22:33 CET 2004

I need to specify error terms properly in a mixed-effects anova model. I 
know you can add error terms in aov using Error and can specify random 
factors in lme but I am not sure how these get treated.

When making the calculations for fixed and random factors, are the correct 
error terms used and how can you get aov or lme to use different error 
terms for fixed and random effects?

I'm basing the need for this on this table from Zar,

Both fixed factors - both tested against error
Both random factors - both tested against interaction MS
1 fixed - interaction MS
1 random - replicate MS

for random you can use error if the interaction is not significant (I have 
been told). 

I want to make sure that the correct error terms are always being used.

Thanks for your help

Nathaniel Street
         University of Southampton
Plants and Environment Lab
     School of Biological Sciences
Basset Crescent East
SO16 7PX
    tel: +44 (0) 23 8059 4387
 fax: +44 (0) 23 8059 4459
      n.r.street at soton.ac.uk
     ICQ: 203465793

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