Hi everyone! I am doing a 2 x 3 (Discrimination x Condition) repeated measures ANCOVA, in SPSS where my covariate is "Language test". I found a main effect of "Discrimination", and an interaction between "Discrimination * Language test", what does this interaction mean? How can I interpret it?
The information you seek is in the coefficient tables, which in some statistics software you have to request expicitly (oddly enough). Note that if you are using treatment contrasts, then there is nothing such as a main effect. It rather is the mean of a reference group. That is denoted the Intercept and all other coefficients are differences to that.
In my online book I explain interaction effects in some depth (chapter 5.5).
https://www.researchgate.net/project/Book-New-statistics-for-the-design-researcher
Hi Eylul. Given that you are using SPSS, you may find this letter helpful.
Article Use of covariates in randomized controlled trials
Cheers,
Bruce
Thank you very much for your help! These sources are quite useful. Bruce Weaver Martin Schmettow
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