
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21831.14    173.3061    22782.34    21491.44    22170.84
experime |  17,281     21817.1    172.9498    22735.49     21478.1     22156.1
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            14.03771      244.84               -465.8567    493.9321
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    diff = mean(control) - mean(experime)                         t =   0.0573
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.5229         Pr(|T| > |t|) = 0.9543          Pr(T > t) = 0.4771
