I'm following-up on this great answer. Essentially, I was wondering how could misspecification of random-effects bias the estimates of fixed-effects?
So, can the same set of fixed-effect coefficients become biased if we create models that only differ in their random-effect specification?
Also as a conceptual matter, can we say in mixed-effect models, the fixed-effect coef is some kind of (weighted) average of the individual regression counterparts fit to each individual cluster and that is why fixed-effect coefs in mixed models can prevent something like this Simpson's Paradox case from happening?
A possible R
demonstration is appreciated.