
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21975.58    174.0786    22883.89    21634.37    22316.79
experime |  17,281    21672.66    172.1645    22632.26     21335.2    22010.12
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            302.9193    244.8346               -176.9645     782.803
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    diff = mean(control) - mean(experime)                         t =   1.2372
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.8920         Pr(|T| > |t|) = 0.2160          Pr(T > t) = 0.1 080
