
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21827.96    172.5403    22681.67    21489.77    22166.16
experime |  17,281    21820.28    173.7138    22835.93    21479.78    22160.77
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            7.685689      244.84               -472.2087    487.5801
------------------------------------------------------------------------------
    diff = mean(control) - mean(experime)                         t =   0.0314
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.5125         Pr(|T| > |t|) = 0.9750          Pr(T > t) = 0.4875
