[R] simple main effect.

[RICHARD M. HEIBERGER]

> Lets take for example an experiment in which I had two between subject
> variables - Strain and treatment, and one within - exposure. all the
> variables had 2 levels each.
>
> I found an interaction between exposure and Strain and I want to compare
> Strain A and B under every exposure (first and second).
> The general model was with that function:
> aov(duration~(Strain*exposure*treatment)+Error(subject/exposure),data)
>
> in summary(aovmodel) there was a significant interaction between exposure
> and strain.
> how (using those HH packages) can I compare Strains under the conditions of
> exposure?

Your example is structurally similar to the maiz example in ?MMC.
Therefore the answer will also be similar.  It is not possible to do
any more without the exact
structure of your data.  As I indicated before, the duration variable
can be random numbers.
I need the full dataset with the actual values for Strain, exposure,
treatment, and subject.
You are welcome to use A,B,C,D for treatment levels and 1,2,...,n for
subject ID.

Rich