Compare group difference with replicates?

Question

I have a measurement for two groups of subjects where each subject contains 3 replicates. For example, the data is like below:

Group Subject Replicate Value
1 A 1 0.2
1 A 2 0.3
1 A 3 0.25
1 B 1 0.4
1 B 2 0.3
1 B 3 0.7
2 C 1 0.2
2 C 2 0.1
2 C 3 0.3
2 D 1 0.4
2 D 2 0.2
2 D 3 0.25

I am thinking of using ANOVA where the subject is the error term,e.g. aov(Value~Group+Error(Subject)) in R. Is it correct?

Thanks! Gim

Answer 1

To me it looks essentially correct. You still have to specify the data.frame the values are taken from in aov like

aov(Value~Group+Error(Subject), data)

This model assumes that subject were taken at random (within their group). It is justified to drop the variable "replicate" from the formula as it bears no information.