
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21898.38    174.1013    22886.87    21557.12    22239.64
experime |  17,281    21749.86    172.1474    22630.02    21412.44    22087.29
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            148.5189    244.8387                -331.373    628.4107
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    diff = mean(control) - mean(experime)                         t =   0.6066
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.7279         Pr(|T| > |t|) = 0.5441          Pr(T > t) = 0.2721
