[R] ANCOVA with defined error terms
hpdutra
hpdutra at yahoo.com
Sat Aug 22 17:36:35 CEST 2009
Thank you Richard, this works. But, the model you suggested me lacks some
between subjects interactions, namely:
veget:time:block
fruit:time:block.
According to Sokal and Rohlf I need to report those as well.
Also, any ideas why the sum of squares on my model are different from yours
summary(mymodel<-(aov(mice~veget*fruit*time+(time*block)+(time*block*veget)+(time*block*fruit)+coon+Error(block/plot,
data = track))))
reports veg:fruit with a sum squares of 80.5
while yours
summary <- (ricsmodel<-aov(mice ~ coon + block*veget*fruit*time -
block:veget:fruit:time+ Error(block/plot), data = track))
gives me a veget:fruit sum of squares of 253.2
the residuals degrees of freedom also differ my model gives 4 DF for the
between subjects while yourr does not report one for the between subjects.
I know I'm asking too much, but I'm just trying to understand.
Thanks
Beto
s
Richard M. Heiberger wrote:
>
> Yes, I meant summary(). anova() isn't defined for aovlist objects and
> summary() is.
>> Warning message:
>> In aov(kotz.mice ~ kotz.coon + block * veget * fruit * time -
>> block:veget:fruit:time + :
>> Error() model is singular
>>
>
> You will need to investigate the singular Error() model. You might want
> to use the simpler Error model
>
> Error(block)
>
> My guess is the plot term is redundant.
>
> What are kotz.mice? That variable isn't in the model you showed.
>
> For more detailed help you will need to
> "provide commented, minimal, self-contained, reproducible code."
>
>
> Rich
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
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