Let's say we have a following prediction:
mod <- y ~ x + (1+x | Subject)
Is there a way to predict new values in y, using the predict() function not by specifying only new fixed effects by using newdata arguement, but also by specifying a single random intercept value for which the predictions should be calculated?
According to my logic it should look something like this:
predict(mod, newdata = data.frame(x = seq(1,10, length.out=100), Subject$'(Intercept)' = 2)