Assume that we have two very small populations that can be written as 

y_1,1 = 15, y_1,2 = 17, y_1,3 = 16, y_2,1 = 11, y_2,2 = 9, y_2,3 = 10. Find µ₁, µ₂, ɛ_1,1, ɛ_1,3, and ɛ_2,1. 

The double subscripts on the observed responses: y_1,1 is read as “y one one.” The first sub-script tells us that the observation was from the first group, and the second subscript tells us the observation number. For example, y_1,j is the jth observation from the first group.