
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281     21832.1    173.0566    22749.54    21492.89    22171.31
experime |  17,281    21816.14    173.1994    22768.31    21476.66    22155.63
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            15.95478      244.84               -463.9396    495.8492
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    diff = mean(control) - mean(experime)                         t =   0.0652
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.5260         Pr(|T| > |t|) = 0.9480          Pr(T > t) = 0.4740
