# 3) Checking model assumptions####
# Checking for M8
# A. Look at independence: plot fitted values vs residuals
E1 <- resid(M8)
F1<-fitted(M8)
plot(x = F1, 
     y = E1, 
     xlab = "Fitted Values",
     ylab = "Normalized residuals")
abline(h = 0, lty = 2)