
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281     21837.5    172.5099    22677.67    21499.36    22175.64
experime |  17,281    21810.74    173.7439    22839.89    21470.19     22151.3
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            26.76022      244.84               -453.1341    506.6545
------------------------------------------------------------------------------
    diff = mean(control) - mean(experime)                         t =   0.1093
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.5435         Pr(|T| > |t|) = 0.9130          Pr(T > t) = 0.4565
