> what are the TWO treatments?
I don't actually know off-hand, I didn't conduct the study - I'm just
helping to analyse the data. I'll find out and let you know ASAP.
>
> if what i see here is right ...
>
> 1. you have pre and post
> 2. weak and strong
> 3. treatment 1 and 2??????
>
> if you have randomly assigned Ss to the 2 levels of #3 ... and then sorted
> the Ss into weak/strong for purposes of analysis ...
>
> you would have a blocking variable for level of ability ... low/high
>
> this would call for (if i am reading it correctly) a 2 by 2 by 2 anova ...
> that's one way to do it with #1 being a within Ss factor ... and #2 and #3
> being between Ss factors ....
>
> the interactions might be of most difference ... asking if the weak or
> strong change the most ... while perhaps ALL change ... it a positive
> direction
>
I've thought about an appropriate ANOVA model and the best I can come up
with is:
Yijk = mew + Ai + Bj + ABij + Eijk
Ai: a fixed factor representing the treatments (2 levels)
Bj: a fixed factor representing prior perfromance (2 levels)
ABij: an interaction between Ai and Bj
Yijk: the score of the kth child who received treatment i and is from group
j
Eijk: random error
However, I suspect that this model is inapporpriate, as the Eijk term will
represent between subjects (children) variation, which AFAIK should not be
included in the estimate of random error.
===========================================================================
This list is open to everyone. Occasionally, less thoughtful
people send inappropriate messages. Please DO NOT COMPLAIN TO
THE POSTMASTER about these messages because the postmaster has no
way of controlling them, and excessive complaints will result in
termination of the list.
For information about this list, including information about the
problem of inappropriate messages and information about how to
unsubscribe, please see the web page at
http://jse.stat.ncsu.edu/
===========================================================================
