Rich, Walmes,
Thank you for enriching my understanding of the concept of
interaction: succinctly and clearly explained. I feel i can better
phrase my question, the context being much clearer now.
In my case, i want to see the simple effects of changing levels of time,
whilst holding
[Reposting to list]
Thank you Rich.
I still don't get it.
If i understand correctly- the MMC example on maize data outlines an
issue with the multiple ties between group means. As a result of this,
user specified contrasts needed specifying.
Its this part, understanding the design matrix
Take a look at contrast package. It has functions to handle with user
contrasts. Below you have a reproducible and minimal example using
contrast's functions.
da - expand.grid(A=factor(paste(A, 1:3, sep=)),
B=factor(paste(B, 1:4, sep=)), rep=1:4)
eta - model.matrix(~A*B,
Karl,
The definition and interpretation of contrasts is part of any intermediate
design of
experiments text.
Contrasts for interactions say that the effect of moving
from level 1 of A to level 2 of A depends on the level of B.
I will use notation YAB to indicate the levels of A and B.
For
Esteemed R-forum subscribers,
I'm having a tough time configuring contrasts for my 3-way ANOVA. In short:
I don't know how to configure (all) my contrasts correctly in order to
specify (all) my comparisons of interest.
I succeeded getting my contrasts of interest set up for a simpler 2-way
Please look at the maiz example, the last example in ?MMC in the HH package.
Follow the example all the way to the end. It illustrates a problem and
then the resolution
of the problem.
install.packages(HH) ## if you don't have it yet.
library(HH)
?MMC
Rich
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