
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21837.93    172.1149    22625.74    21500.56    22175.29
experime |  17,281    21810.32    174.1352    22891.33    21468.99    22151.64
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            27.60957      244.84               -452.2847    507.5039
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    diff = mean(control) - mean(experime)                         t =   0.1128
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.5449         Pr(|T| > |t|) = 0.9102          Pr(T > t) = 0.4551
