# F-test for difference in two population variances

• Two population variance test has 3 different forms:

• Two Tailed Test:

• Lower Tail test:

• Upper Tail Test

• The F test statistic is:

• Although itâ€™s not a rule but always take the higher sample variance as the numerator and lower sample variance as the denominator

= Variance of Sample 1

(n1 â€“ 1) = numerator degrees of freedom

= Variance of Sample 2

(n2 â€“ 1) = denominator degrees of freedom