
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21959.69    174.3726    22922.54     21617.9    22301.47
experime |  17,281    21688.56    171.8683    22593.32    21351.68    22025.44
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            271.1289    244.8357                -208.757    751.0148
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    diff = mean(control) - mean(experime)                         t =   1.1074
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.8659         Pr(|T| > |t|) = 0.2681          Pr(T > t) = 0.1341
