Specifying error terms in aov and lme
Nathaniel Street <N.R.STREET at soton.ac.uk> writes:
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?
In short: Those considerations make sense for programs that give you only a partitioning of the sum of squares. aov() and lme() should (mostly) get things right automatically *if* you specify the model correctly. With aov() you still need some know-how to test significance of variance components, though.
I'm basing the need for this on this table from Zar, Both fixed factors - both tested against error
Now that can actually be horribly wrong if there is significant interaction.
Both random factors - both tested against interaction MS 1 fixed - interaction MS 1 random - replicate MS
wrong again.....
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907