|
|  |
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
re: st: Re: Anova and contrasts
I am interested in looking at the system*material interactions in
more detail. I have carried out "all possible" comparisons using:
.. test _coef[system[1]*material[1]]=_coef[system[1]*material[2]]
etc.
It occurs to me that I should setup a contrast matrix test this
using the mtestand allow for multiple testing. The problem is that
the design matrix has 54 columns. Do I need to set up this matrix
for the 4 comparisons that I need or is there a more efficient (or
simpler) approach.
Many thanks.
When you get a significant interaction, there are two ways to follow
it up. One is with simple main effects, the other is with interaction
contrasts. Seems you are doing the latter, and you see the prospect
of typing in a big matrix annoying? Is that the question? Maybe there
is a quicker way to type that in? I'd be interested in the answer
too. You might also try the look at simple main effects with the
command sme (findit sme). An example is at UCLA:
http://www.ats.ucla.edu/stat/Stata/faq/sme.htm
Another possibility, if you have done all comparisons as you said, is
to pass those statistics or p values to a multiple test correction
command like smileplot (findit smileplot).
-Dave
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
