# f test!

#### waqasemran

##### New Member
In analysis of varience.
whay we use mostly single tailed,one tailed f test.why dont we use the two tailed.
and under which konditions we use the alternative hypothesis that.alll the means are not equal , or, atleast two means are equal.
in anova.
thanku

#### JohnM

##### TS Contributor
Because the vast majority of the time, we're looking for evidence of differences, not evidence of equivalence.