<P> are random variables each with expected value μ, and let </P> <Dl> <Dd> X _̄ n = X 1 + ⋯ + X n n (\ displaystyle (\ overline (X)) _ (n) = (X_ (1) + \ cdots + X_ (n) \ over n)) </Dd> </Dl> <Dd> X _̄ n = X 1 + ⋯ + X n n (\ displaystyle (\ overline (X)) _ (n) = (X_ (1) + \ cdots + X_ (n) \ over n)) </Dd> <P> be the "sample mean ." Then the quantities </P>

Short notes on one way classification in statistical survey