
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21939.72    174.1321    22890.92     21598.4    22281.03
experime |  17,281    21708.53    172.1136    22625.57    21371.17    22045.89
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |              231.19    244.8368               -248.6982    711.0782
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    diff = mean(control) - mean(experime)                         t =   0.9443
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.8275         Pr(|T| > |t|) = 0.3450          Pr(T > t) = 0.1725
