
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21917.21    173.0798    22752.58    21577.95    22256.46
experime |  17,281    21731.04    173.1734    22764.89     21391.6    22070.47
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            186.1688     244.838               -293.7216    666.0592
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    diff = mean(control) - mean(experime)                         t =   0.7604
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.7765         Pr(|T| > |t|) = 0.4470          Pr(T > t) = 0.2235
