model matrix for mixed model what is the model matrix for a mixed model mm model.matrix() what is the model matrix what is the model matrix? what is the data what is the model matrix what is the function of the model matrix mixed model matrix how to get mixed models what is the model matrix of mixed models? what is the function of mixed model what is the model matrix for a mixed mixed model what is the function of mm-model.matrix model matrix of mixed model how to fit in mm model matrix which statement is an appropriate fit to mm-model.matrix? what is the mixed model matrix for a model what is mixed model matrix how to do model matrix fit mixed model of model matrix when to use mm model matrix