The tail refers to the end of the distribution of the test statistic for the particular analysis that you are conducting. ... This means that analyses such as ANOVA and chi-square tests do not have a “one-tailed vs. two-tailed” option, because the distributions they are based on have only one tail.

How do you know if a test is one tailed or two tailed?

A one-tailed test has the entire 5% of the alpha level in one tail (in either the left, or the right tail). A two-tailed test splits your alpha level in half (as in the image to the left).

Is F-test always two tailed?

To conclude: When comparing two groups, an F-test is always one-sided, but you can report a (more powerful) one-sided t-test - as long as you decided this before looking at the data.