On 4/20/2014 5:29 PM, Anoop Balachandran wrote:
> I have two randomized groups (exercise) in a pre-post design.
>
> I wanted to find out what is the best statistical analysis for such a
> design. I just wanted to do a regular repeated measures ANOVa, but
> the more I read, the more I get the feeling that ANCOVA is the best
> option with pre-test as a covariate. My outcome measure at baseline
> is different for each group ( not significant) , so I assume ANCOVA
> is a better option. I am guessing the reason for ANCOVA is better
> statistical power and for equalizing baseline scores.
>
> Does anyone have any information about it or any good books that
> might help? I tried reading some relevant papers but just found it
> hard to wrap around the full concept.
Sorry for the late response. There is a third choice: change scores. All
of your choices are controversial and there is no consensus in the
research community on how to handle this. Using the baseline as a
covariate is probably the least controversial approach. But there is an
excellent book which outlines all of your choices and their implications.
Pepter L. Bonate (2000). Analysis of Pretest-Posttest Designs. Chapman&
Hall/CRC. ISBN: 1-58488-173-9
Steve Simon, [log in to unmask], Standard Disclaimer.
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