
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21640.53    171.8003    22584.38    21303.79    21977.28
experime |  17,281    22007.71    174.4345    22930.67     21665.8    22349.62
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |           -367.1757     244.832               -847.0545    112.7031
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    diff = mean(control) - mean(experime)                         t =  -1.4997
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.0669         Pr(|T| > |t|) = 0.1337          Pr(T > t) = 0.9331
