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Re: st: Re: ST: one-tailed test


From   Richard Williams <Richard.A.Williams.5@nd.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Re: ST: one-tailed test
Date   Mon, 11 Oct 2004 08:20:01 -0500

At 08:57 AM 10/11/2004 -0400, Eric Uslaner wrote:
Levy Lee asks how to perform a one-tailed test after a regression and
Richard Williams responds: "ust look at the printout, and see (a) is
the coefficient for x2 positive, and (b) is it significant at the .10
level  (or double whatever alpha level it is you want to chose).  You
don't need
to do any additional analyses, the information you need is already
there."

Well, not quite.  Stata (annoyingly) always reports 2-tailed tests,
whereas one-tailed tests are clearly more appropriate.  So you need to
divide the p level by 2.
Same thing. Divide .10 by 2 and you get .05. So, either look for 2-tailed sign. levels that are twice as high as the 1-tailed sign. level you want to use, or divide the reported sign. level by 2.


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Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
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EMAIL: Richard.A.Williams.5@ND.Edu
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