
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21965.98    175.2571     23038.8    21622.46     22309.5
experime |  17,281    21682.26    170.9657    22474.67    21347.15    22017.37
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            283.7169    244.8352               -196.1681     763.602
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    diff = mean(control) - mean(experime)                         t =   1.1588
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.8767         Pr(|T| > |t|) = 0.2465          Pr(T > t) = 0.1233
