
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21912.75    174.0305    22877.56    21571.63    22253.87
experime |  17,281    21735.49    172.2182    22639.32    21397.93    22073.06
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            177.2564    244.8381               -302.6344    657.1472
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    diff = mean(control) - mean(experime)                         t =   0.7240
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.7655         Pr(|T| > |t|) = 0.4691          Pr(T > t) = 0.2345
