R help - Dec 2009 - simple main effect.

Hi, I'm a bit new to R and I would like to know how can I compare simple
main effects when using the aov function.
I'm doing a mixed model ANOVA with two between subjects variables and one
within.
When I get an interaction of two of the variables I don't know how to check
for simple main effect of that interaction (A at B1 and A at B2 for
example).
The aov function is very simple but for some reason I can't find how to do
this.
Thank you very much.
Or Duek.

	[[alternative HTML version deleted]]

Try going through this:
http://www.personality-project.org/r/r.anova.html

<http://www.personality-project.org/r/r.anova.html>


----------------Contact
Details:-------------------------------------------------------
Contact me: Tal.Galili@gmail.com |  972-52-7275845
Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) |
www.r-statistics.com/ (English)
----------------------------------------------------------------------------------------------




On Sat, Dec 19, 2009 at 7:27 PM, Or Duek <orduek@gmail.com> wrote:
> Hi, I'm a bit new to R and I would like to know how can I compare
simple
> main effects when using the aov function.
> I'm doing a mixed model ANOVA with two between subjects variables and
one
> within.
> When I get an interaction of two of the variables I don't know how to
check
> for simple main effect of that interaction (A at B1 and A at B2 for
> example).
> The aov function is very simple but for some reason I can't find how to
do
> this.
> Thank you very much.
> Or Duek.
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@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.
>
	[[alternative HTML version deleted]]

For simple effects in the presence of interaction there are several
options included in the HH package.  If you don't already have the HH
package, you can get it with
   install.packages("HH")

Graphically, you can plot them with the function
   interaction2wt(..., simple=TRUE)
See the examples in
   ?HH::interaction2wt

For tests on the simple effect of A conditional on a level of B, you
can use the model formula B/A and look at the partition of the sums of
squares using the split= argument
   summary(mymodel.aov, split=<put your details here>)

For multiple comparisons from designs with Error() terms, you need to
specify the same sums of squares with an equivalent formula that doesn't 
use the Error() function.  See the maiz example in
   ?HH::MMC
Read the example all the way to the end of the help file.

Rich