why should an experiment use varying slopes why are slope variations important what is the importance of random variation across all variables in mixed-effects when is a fixed effect significant which is the best reason to use varying random slopes in a mixed effect model? why are random variations important why does an mixed effect model vary when does varying coefficients in a mixed effect model lose significance why do mixed effects models vary between levels how to interpret varying slopes why is varying the slope important in mixed effect simulations? when is it wise to exclude variable and fixed slopes when do slopes of a mixed-effects variable differ why do slopes vary in mixed effects model? when does a variable variable variation lose significance why is variability in random effects necessary? what level should an variable effect be for an average mixed effect what is the significance of varying slopes in a mixed effects model do you have to vary a fixed effect for mixed models what is the significance of varying variables in mixed effect