I am not clear as to how to assess if a multilevel model fit using
lmer satisfies the assumptions of normality and homoscedasticity?
I have used the following
r code and I find that histogram of residuals and qq plot satisfy the assumption that residuals are normally distributed. But as multilevel models have residual both at individual level as well as at the group level, should the residuals at both the levels be normally distributed?
residuals <- resid(results) summary(residuals) hist(residuals) qqnorm(residuals) qqline(residuals) xyplot(resid(results) ~ fitted(results))