Pre-post intervention

[Nuria Calet]

Hello,

I have a pre-post desing intervention with 2 interventin groups and 1 control group. I carried out a 3X2 repeated measured ANOVA, but just the interaction was significant so I did the simple main effects to analyze the interaction and I get good results. But I wonder if it is better to use a ANCOVA with the pretest measures as a covariate. I tried but I get better results with the simple main effect.

What is the best analysis or test?

 

Thanks a lot, Nuria

[Henry Steel]

Nuria

I think the ANCOVA will be appropriate only if the pre-test measures between the three groups were significantly different. If not I think the repeated measures ANOVA is fine.

Henry

[Nuria Calet]

Hello Henry,

 

Thanks for your reply, but one of the assumptions in ANCOVA is that it can’t be significantive difference between the groups in the covariate, so if I had significantive difference, I couldnt use it.

 

Nuria

[Henry Steel]

Nuria

This is a helpful link.  https://www-304.ibm.com/support/docview.wss?uid=swg21476717

Henry

[Author]

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