repeated measures MANOVA or MANCOVA?


The study is pretest-posttest control group design, comparing two treatments and a control group (wait list) on 7 outcome variables using a convenience sample with random assignment to the 3 groups (level of treatment is the independent variable). The outcome variables (continuous) are scores from two measures (with established validity and reliability), 1 measure with 1 total score and 1 measure with 5 subscale and 1 total score. Treatment is 6 weeks long. Participants may have been exposed (participated/practiced on their own) to one or both treatments in the past. Also, the measures have strong face validity, so the participants may be sensitized to what is being assessed/studied - the measures are the same on pre and post.

The question in this case is whether repeated measures MANOVAs (within and between) or MANCOVAs using pre-test scores as covariate would be a better choice, or put differently, what would make one more appropriate than the other... and would it at all make sense to do both (i.e. MANCOVA as a confirmatory test)? Thank you in advance for any suggestions and ideas.