
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21957.71    173.6963    22833.63    21617.25    22298.17
experime |  17,281    21690.53    172.5519    22683.19    21352.31    22028.75
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            267.1758    244.8358               -212.7103     747.062
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    diff = mean(control) - mean(experime)                         t =   1.0912
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.8624         Pr(|T| > |t|) = 0.2752          Pr(T > t) = 0.1376
