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


From   "Levy Lee" <chtl@econ.hku.hk>
To   <statalist@hsphsun2.harvard.edu>
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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