# One Tail Tests

#### Yida

##### New Member
Is there anyway to output one tail test pvalues for running OLS regressions?

Also, using ivreg2 and outreg2, I get a row of results that are "r2_a". I assume this is adjusted r-squared?

#### Dason

What do you mean by a one tail test for OLS regression? A one tail test of individual parameters? Just testing if they're positive or something like that?

#### Yida

##### New Member
For a two tail test, a pvalue could be say .5
In a one tail test, the pvalue would be .25

For a two tail test with a pvalue of -.8
The one tail pvalue would be .6 (which is 1-.8/2)

#### Dason

For a two tail test, a pvalue could be say .5
In a one tail test, the pvalue would be .25

For a two tail test with a pvalue of -.8
The one tail pvalue would be .6 (which is 1-.8/2)
Except both of those depend on the direction of the test. In your first example the one-tailed p-value could be .75 if the direction of the effect is the opposite of what was hypothesized.

#### bukharin

##### RoboStataRaptor
Also, using ivreg2 and outreg2, I get a row of results that are "r2_a". I assume this is adjusted r-squared?
Yes. Assuming you're using the -regress- command, this is documented in -help regress- (see the "Saved results" section at the end of the help file)

#### Yida

##### New Member
I am assuming one direction for all the tests.