
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21944.44    174.0007    22873.65    21603.38     22285.5
experime |  17,281     21703.8     172.246    22642.99    21366.18    22041.42
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            240.6442    244.8366               -239.2435    720.5319
------------------------------------------------------------------------------
    diff = mean(control) - mean(experime)                         t =   0.9829
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.8372         Pr(|T| > |t|) = 0.3257          Pr(T > t) = 0.1628
