<Dl> <Dd> S X 2 = 1 n − 1 ∑ i = 1 n (X i − X _̄) 2 and S Y 2 = 1 m − 1 ∑ i = 1 m (Y i − Y _̄) 2 (\ displaystyle S_ (X) ^ (2) = (\ frac (1) (n - 1)) \ sum _ (i = 1) ^ (n) \ left (X_ (i) - (\ overline (X)) \ right) ^ (2) (\ text (and)) S_ (Y) ^ (2) = (\ frac (1) (m - 1)) \ sum _ (i = 1) ^ (m) \ left (Y_ (i) - (\ overline (Y)) \ right) ^ (2)) </Dd> </Dl> <Dd> S X 2 = 1 n − 1 ∑ i = 1 n (X i − X _̄) 2 and S Y 2 = 1 m − 1 ∑ i = 1 m (Y i − Y _̄) 2 (\ displaystyle S_ (X) ^ (2) = (\ frac (1) (n - 1)) \ sum _ (i = 1) ^ (n) \ left (X_ (i) - (\ overline (X)) \ right) ^ (2) (\ text (and)) S_ (Y) ^ (2) = (\ frac (1) (m - 1)) \ sum _ (i = 1) ^ (m) \ left (Y_ (i) - (\ overline (Y)) \ right) ^ (2)) </Dd> <P> be the sample variances . Then the test statistic </P> <Dl> <Dd> F = S X 2 S Y 2 (\ displaystyle F = (\ frac (S_ (X) ^ (2)) (S_ (Y) ^ (2)))) </Dd> </Dl>

Test for equality of variance in two samples