# Nesting in experimental desing

Suppose I have following results from my 2 experiments that contain 3 Block each and there are 4 treatments per Block (the example is R based)

dft <- data.frame(Exp = rep(1:2, each = 12),
Block = rep(rep(1:3, each = 4), each = 2),
Treat = rep(1:4, 6),
Plot = rep(1:12, 2),
y = rnorm(24, mean = 10, sd = 2))


I want to find out if there are differences between Treat and Exp. I used folowing model

library(nlme)
myMod <- lme(y ~ Exp*Treat, random = ~1|Block/Plot, data = dft, method = "ML")


but I got the comment that I should include Block nested in Exp in my model I did that too

myMod1 <- lme(y ~ Exp/Block + Exp*Treat, random = ~1|Block/Plot, data = dft, method = "ML")


and than compare both models which were not significantly different

anova(myMod, myMod1)


if there are no differences which model is more logical in this case???

• The simplest one. – user2974951 Feb 5 '19 at 8:38