
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21983.28    174.6808    22963.06    21640.89    22325.67
experime |  17,281    21664.96    171.5526    22551.83     21328.7    22001.22
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            318.3231     244.834               -161.5596    798.2057
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    diff = mean(control) - mean(experime)                         t =   1.3002
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.9032         Pr(|T| > |t|) = 0.1936          Pr(T > t) = 0.0968
