
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21866.67    172.1481    22630.11    21529.24     22204.1
experime |  17,281    21781.57    174.1018    22886.94    21440.32    22122.83
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            85.09687    244.8396               -394.7967    564.9904
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    diff = mean(control) - mean(experime)                         t =   0.3476
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.6359         Pr(|T| > |t|) = 0.7282          Pr(T > t) = 0.3641
