Can I use "mixed ancova with repeated measures"in this case?

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roshanak
Posts: 1
Joined: Tue Sep 02, 2014 6:01 pm

Can I use "mixed ancova with repeated measures"in this case?

Postby roshanak » Tue Sep 02, 2014 6:13 pm

Hi everybody,
I have 4 separated groups (4 different interventions), and I measured the dependent variable over 4 time points. I considered my intervention groups as "between subjects factor" and the time points as "within subjects factor". I realized that there was a significant difference in pre-test.

So I chose this method: mixed ANCOVA with repaeted measures: 4 (intervention groups, between subject factor) * 3 (time points, within subject factor), and the pre-test as covariate (in order to control initial differences)

My consulting adviser said it is false, because there are more than 2 time points and we can't use ANCOVA in this case.

Is it wrong or right? If it's wrong, would you suggest me any appropriate method, please?
GerineL
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Joined: Tue Jun 10, 2008 4:50 pm

Re: Can I use "mixed ancova with repeated measures"in this c

Postby GerineL » Tue Sep 16, 2014 9:44 am

This seems right to me (at least, I don't see why you could not use repeated measures ancova).
However, why do you use pre-test as a covariate and not as a first measure?

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