
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21886.76    173.3638    22789.93    21546.95    22226.57
experime |  17,281    21761.48    172.8906    22727.72     21422.6    22100.37
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            125.2781    244.8391               -354.6145    605.1706
------------------------------------------------------------------------------
    diff = mean(control) - mean(experime)                         t =   0.5117
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.6956         Pr(|T| > |t|) = 0.6089          Pr(T > t) = 0.3044
