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Re: st: RE: outreg/estimates type commands for ttest


From   Nishant Dass <nishant_dass@yahoo.com>
To   STATA Help <statalist@hsphsun2.harvard.edu>
Subject   Re: st: RE: outreg/estimates type commands for ttest
Date   Thu, 24 Aug 2006 06:25:54 -0700 (PDT)

Nick,

Thank you very much for your elaborate answer.
The loop with -display- that you suggested was very
helpful.

Nishant


--- Nick Cox <n.j.cox@durham.ac.uk> wrote:

> In the case of t tests, a work-around is obtained
> by noting that the results of 
> 
> regress <response> <binary variable>
> 
> are equivalent to 
> 
> ttest <response>, by(<binary variable>) 
> 
> so that -outreg- or -estout- (which I think 
> you mean here rather than -estimates-) can then be 
> used. 
> 
> Alternatively, a knit-it-yourself approach is 
> very simple: 
> 
> . foreach v of var price-gear {
>   2. qui ttest `v', by(foreign)
>   3. di as txt "`v'" "{col 22}" as res %6.3f  r(t) "     
>    "  %5.4f  r(p)
>   4. }
> price                -0.414         0.6802
> mpg                  -3.631         0.0005
> rep78                -6.016         0.0000
> headroom              2.609         0.0110
> trunk                 3.268         0.0017
> weight                6.246         0.0000
> length                5.890         0.0000
> turn                  6.903         0.0000
> displacement          6.597         0.0000
> gear_ratio           -8.476         0.0000
> 
> The essentials: 
> 
> 0. Looping over a variable list. 
> 
> 1. -quietly- executing your statistical command. 
> 
> 2. Picking up r() stuff (or indeed e() stuff) left in
> memory. 
> You can -return list- or -ereturn list- or read the
> manual 
> entry. 
> 
> 3. -display-ing results, with some attention to layout
> and 
> formats. 
> 
> The example above is the third iteration of a real
> example. I 
> guessed lucky at r(p) and r(t) and then made changes to 
> the layout and formats. 
> 
> At this point you may want to transfer to your text or 
> word processor. 
> 
> Although I have mixed feelings about the program, 
> I note that -makematrix- from SSC gets you there 
> too:
> 
> . makematrix , from(r(p) r(t)) : ttest price-gear,
> by(foreign)
> 
>                        p           t
>        price   .88738723   .14215113
>          mpg   .00008982  -4.1688344
>        rep78   8.313e-08  -6.0162381
>     headroom   .00494105   2.9071556
>        trunk   .00055112   3.6288312
>       weight   2.047e-09   6.9268345
>       length   2.461e-08   6.3182882
>         turn   1.721e-10   7.5259982
> displacement   3.629e-09   6.7875143
>   gear_ratio   1.590e-12  -8.6552193
> 
> . makematrix results , from(r(p) r(t)) format(%6.3f) :
> ttest price-gear, by(foreign)
> 
> results[10,2]
>                    p       t
>        price   0.887   0.142
>          mpg   0.000  -4.169
>        rep78   0.000  -6.016
>     headroom   0.005   2.907
>        trunk   0.001   3.629
>       weight   0.000   6.927
>       length   0.000   6.318
>         turn   0.000   7.526
> displacement   0.000   6.788
>   gear_ratio   0.000  -8.655
> 
> In this case, it is fortunate that 3 d.p. work fairly
> well for both p and 
> t values. But then with most statistical results 3 d.p.
> often work well, 
> although we frequently show many more places as a matter
> of social ritual. 
> 
> Nick 
> n.j.cox@durham.ac.uk 
> 
> Nishant Dass
>  
> > Is anyone aware of a command (like "outreg" or
> "estimates")
> > that I could use to tabulate "ttest" or "median" test
> > results?
> > 
> > Although I don't think there's one, I just wanted to
> > confirm.  
> 
> *
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> 


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