I have this model:
brm(bf(Y ~ intercept + x * slope * setting, intercept ~ 1 + (1|id_f), slope ~ 1 + (1|id_f), setting ~ setting_c, nl = TRUE))
setting_c is a factor with 4 levels.
I want the first level to have an effect of 1 (no effect when it is multiplied with
slope), and the remaining 3 levels to be estimated.
Is it possible to specify this?
(Also, is it possible to specify this model as a linear model?)