
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21865.48    173.5199    22810.44    21525.36    22205.59
experime |  17,281    21782.76    172.7347    22707.22    21444.19    22121.34
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            82.71288    244.8396               -397.1807    562.6065
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    diff = mean(control) - mean(experime)                         t =   0.3378
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.6323         Pr(|T| > |t|) = 0.7355          Pr(T > t) = 0.3677
