• ^asg observations having sample mean y, explain why E(« - y)7(s -1)

estimates the variance (T2 jn of the sampling distribution of the y,-values.

(b) Using (a), explain why 2«(y/ - y)2

/(g - 1)

estimates a 2

. For the unequalsample size case, replacing n by n,- yields the between-groups estimate.