Determining Significance Level
for an F-Test
If you have examined the F-distribution table, you will have noticed that values for two-tailed tests aren't given. To find the rejection regions for a two-tailed test, the procedure is simple:
- Determine the Significance level .
- Divide that value in half (one-half for each side of the distribution).
- For the right side, simply look up the value in the table, keeping in mind that your significance level is one-half the original.
- For the left side, reverse the values for the numerator and denominator: from n1 /n2 to n2 /n1. Look up these values on the table, at one-half the significance level, and take the reciprocal of that number. This number is the left-side critical value.