[R] ANCOVA with defined error terms
hpdutra
hpdutra at yahoo.com
Thu Aug 20 14:39:44 CEST 2009
Thanks Richard,
I tried running the analysis the way you suggested but here is the error
that I get
> track.aov <- aov(mice ~ coon+block*veget*fruit*time -
> block:veget:fruit:time
+ + Error(block/plot), data = track)
Warning message:
In aov(kotz.mice ~ kotz.coon + block * veget * fruit * time -
block:veget:fruit:time + :
Error() model is singular
> anova(track.aov)
Error in UseMethod("anova") : no applicable method for "anova"
I'm not sure you can use the function anova for an aov object. I tried
summary and it also didn't work. Did you mean something else?
Thanks
Richard M. Heiberger wrote:
>
> track.aov <- aov(mice ~ coon
> + block*veget*fruit*time - block:veget:fruit:time
> + Error(block/plot), data = track)
> anova(track.aov)
>
>
> I think this is what you are looking for. This model in words says,
> What is the effect of the four-way crossing after adjusting for
> the covariate coon? We don't have enough degrees of freedom for
> the full crossing, so remove the four-way interaction.
>
> anova() gives the sequential sums of squares of (multi-degree of
> freedom) effects. Be sure that the five variables (block, veget, fruit,
> time, plot) are factors. I am assuming time is a factor here.
>
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>
>
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