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

 From "Levy Lee" To Subject st: Re: RE: Re: Re: ST: one-tailed test Date Mon, 11 Oct 2004 21:38:46 +0800

```thanks, NIck

----- Original Message -----
From: "Nick Cox" <n.j.cox@durham.ac.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Monday, October 11, 2004 9:34 PM
Subject: st: RE: Re: Re: ST: one-tailed test

> Not precise???
>
> In cases in which the P-value is left behind as
> a returned value (see results of -return list- or
> -ereturn li-), dividing by 2 will give you
> several decimal digits of precision.
>
> As usual, that precision could be spurious if underlying
> assumptions are not valid, or if data are coarsely or poorly
> measured, etc., but you can get a lot of precision
> out of Stata.
>
> In cases in which there is no such returned P-value,
> you may have to dig down and fire up a function
> or two, but the precision is there in principle.
>
> The key point is that you are _not_ limited to
> taking what is printed out and dividing _that_
> by two.
>
> Nick
> n.j.cox@durham.ac.uk
>
> Levy Lee
>
> > thanks again,
> >
> > but i do not think this is precise, are there other way to go?
> >
>
> Eric Uslaner
>
> > > 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.
>
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```