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st: Question on Ttest.


From   "Joao Pedro W. de Azevedo" <j.p.azevedo@ncl.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Question on Ttest.
Date   Fri, 21 Nov 2003 12:47:07 -0000

Dear Statausers,
I'm doing a simple ttest, however I would like to retrive the Std. Deviation
of the difference of the means (see output below). Does anyone know if Stata
saves this statistic?
Many thanks,
JP 


. ttest  match2291_0== match2291_1 if week>=2144

Paired t test

----------------------------------------------------------------------------
--
Variable |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf.
Interval]
---------+------------------------------------------------------------------
--
matc~1_0 |     127    76.95678    .9025185    10.17087    75.17072
78.74284
matc~1_1 |     127    59.05176    .9798913    11.04281    57.11258
60.99093
---------+------------------------------------------------------------------
--
    diff |     127    17.90502    .2387616    2.690706    17.43252
18.37753
----------------------------------------------------------------------------
--

            Ho: mean(match2291_0 - match2291_1) = mean(diff) = 0

  Ha: mean(diff) < 0         Ha: mean(diff) != 0        Ha: mean(diff) > 0
       t =  74.9912                t =  74.9912              t =  74.9912
   P < t =   1.0000          P > |t| =   0.0000          P > t =   0.0000
r; t=0.18 12:41:07

. return list

scalars:
              r(sd_2) =  11.0428143208466
              r(sd_1) =  10.17086703109571
                r(se) =  .2387615526929942
               r(p_u) =  1.0480080349e-106
               r(p_l) =  1
                 r(p) =  2.0960160698e-106
                 r(t) =  74.99123715134762
              r(df_t) =  126
              r(mu_2) =  59.05175589013287
               r(N_2) =  127
              r(mu_1) =  76.95678011075718
               r(N_1) =  127

----------------------------------------

Joao Pedro W. de Azevedo
School of Business (Economics)             
Ridley Building
University of Newcastle
NE1 7RU                     
United Kingdom

Telephone:  +44 (0) 191 222-5237
Mobile: +44 (0) 7984-060675
Fax:        +44 (0) 191 222-6548
E-mail: j.p.azevedo@ncl.ac.uk 
http://www.students.ncl.ac.uk/j.p.azevedo/


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