
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21896.71     175.242    23036.82    21553.22    22240.21
experime |  17,281    21751.53    170.9862    22477.36    21416.38    22086.68
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            145.1874    244.8388               -334.7046    625.0793
------------------------------------------------------------------------------
    diff = mean(control) - mean(experime)                         t =   0.5930
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.7234         Pr(|T| > |t|) = 0.5532          Pr(T > t) = 0.2766
