diet = c(1,1,1,2,2,2,2,2,3,3,3,3)
diet = factor(diet)
weightgain = c(8,13,9,9,16,21,11,18,15,10,17,6)
boxplot(weightgain~diet) 

summary(aov(weightgain~diet)) 




treatment = c(1,1,1,1,1,2,2,2,2,2,
              3,3,3,3,3,4,4,4,4,4)
treatment = factor(treatment)
weight = c(1.23,0.42,0.55,0.08,1.25,
           0.97,0.96,0.38,0.45,0.97,
           0.06,0.53,0.11,0.77,0.81,
           0.88,1.43,1.15,1.53,1.21)

boxplot(weight~treatment) 

summary(aov(weight~treatment))