
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21867.66    175.2469    23037.46    21524.16    22211.16
experime |  17,281    21780.58    170.9823    22476.86    21445.44    22115.73
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            87.07372    244.8396               -392.8198    566.9672
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    diff = mean(control) - mean(experime)                         t =   0.3556
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.6389         Pr(|T| > |t|) = 0.7221          Pr(T > t) = 0.3 611
