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 Photpe
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 exam
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*
[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
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
[[alternative HTML version
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
A
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