Probably a basic question, but say I have a model Y ~ X1*X2 and both X1 and X2 are continuous. How would I do a directional hypothesis test for the effect of X1, conditioned on the predictor X2 being some arbitrary value, e.g., X2 = 2?

# Brms hypothesis test for term in interaction by condition

**andymilne**#3

Using the `predict`

function? If so, how do I then test the hypothesis (e.g., that the effect of X1 > 0)?