I am running 2 different models with brms and have some difficulties with contrasts.
The first one is with age as a continuous variable, and 4 conditions that I want to compare. Similarly as in lme4 one condition is selected as a reference, but since I have 4 conditions I want the comparisons of all of them together.
Similarly, I have the same model but this time with age group (categorical). Let’s say I put as a reference the adults group, to see whether there is a difference with children for conditions. Can I get the difference between conditions within each group without rerunning the model with a different reference?
What would be the best way to check contrasts between levels of a factor that are not the reference level?