Bayesian RM ANCOVA: no evidence for interaction but simple slope analyses indicates interaction
My model is a 2-level repeated within-subject factor (Repeated), a between-subject factor (Condition) and a covariate (Difference). Basically I want to look at the effects of Condition and Difference on the performances in 2 variants of a task (Repeat 1 and Repeated 2). I expect the effects to be different across the 2 variants.
When I ran a Bayesian RM ANCOVA in JASP all seems to make sense, except for that there was strong evidence against the interaction between Difference and Repeated.
The thing is when I plot the data I could see there's difference between the two lines. So I ran two separate Bayesian linear regressions to double-check. And indeed:
There's no effect of Difference on Repeated 1.
But there's an effect of Difference on Repeated 2.
My question is then: why did I find that there's no evidence for the interaction between Difference and Repeated in the RM ANCOVA?
Thank you for your help in advance!