
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21916.12    172.3302    22654.06    21578.34    22253.91
experime |  17,281    21732.12    173.9193    22862.95    21391.22    22073.02
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            184.0018     244.838               -295.8887    663.8922
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    diff = mean(control) - mean(experime)                         t =   0.7515
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.7738         Pr(|T| > |t|) = 0.4523          Pr(T > t) = 0.2262
