is mixed model causal is mixed effect theory causal what kind of model is mixed effect are fixed random and mixed effects model and multilevel models causal? are mixed effects linear models causal are random variables causal which model is associated with fixed random variables? are the relationships in fixed-random and mixed-effect models causal or not? are random variables causal in multilevel models what type of model is mixed effect model is random and mixed effect model causal are the relations implied by variables in a single-level model causal is the response in the mixed-effect model causal are mixed variable and fixed variable causal is random interaction causal when are all relationships causal what is the relationship between the variable that is the random variable in a mixed effect model and the multilevel variable that is the explanatory variable? why are random random variables used in causal inference? are random variables always causal are mixed effect multilevel models causal