# Is the F test used for testing the difference in two population variances always a one tailed test? Why or why not?

##### 1 Answer

Jul 9, 2017

Yes, it is always one-tailed.

#### Explanation:

The specific "F-distribution" is a skewed curve from which we are trying to determine whether the "F-value" we obtained from our variance comparison is 'random' or not. That is, does it reject my Null Hypothesis or not?

For a useful discussion and graphical examples, see:

http://blog.minitab.com/blog/adventures-in-statistics-2/understanding-analysis-of-variance-anova-and-the-f-test