# B. Look at independence:
# i. plot residuals vs each covariate in the model
# Fish_Length
plot(x = data$Z_Length,
y = E1,
xlab = "Z Length",
ylab = "Normalized residuals")
abline(h = 0, lty = 2)
# Note: observed groupings are created by the nature of the data because in the data set
# we only measured individuals from 5 categories of lengths (big, small, and three groups in between)
# Species
boxplot(E1 ~ Fish_Species,
ylab = "Normalized residuals",
data = data, xlab = "Species")
abline(h = 0, lty = 2)
#Lake
boxplot(E1 ~ Lake,
ylab = "Normalized residuals",
data = data, xlab = "Lake")
abline(h = 0, lty = 2)