[R] lme newbie question

Christoph Lehmann christoph.lehmann at gmx.ch
Fri Jun 11 20:12:52 CEST 2004

I try to implement a simple 2-factorial repeated-measure anova in the
lme framework and would be grateful for a short feedback

-my dependent var is a reaction-time (rt), 
-as dependent var I have 
   -the age-group (0/1) the subject belongs to (so this is a
    between-subject factor), and 
   -two WITHIN experimental conditions, one (angle) having 5, the other
    3 (hands) factor-levels; means each subjects performs on 3 * 5 = 15
    different task diffiulties

Am I right in this lme implementation, when I want to investigate the
influence of the age.group, and the two conditions on the rt:

	my.lme <- lme(rt ~ age.group + angles * hands, data = my.data, random =
~ 1 |subject)

then I think I would have to compare the model above with a more
elaborated one, including more interactions:

	my.lme2 <- lme(rt ~ age.group * angles * hands, data = my.data, random
= ~ 1 |subject)

and comparing them by performing a likelhood-ratio test, yes?

I think, if I would like to generalize the influence of the experimental
conditions on the rt I should define angles and hands as a random
effect, yes? 


thanks for a short feedback. It seems, repeated-measures anova's aren't
a trivial topic in R :)


Christoph Lehmann <christoph.lehmann at gmx.ch>

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