
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21990.62    175.0476    23011.27     21647.5    22333.73
experime |  17,281    21657.63    171.1776    22502.53     21322.1    21993.15
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            332.9893    244.8335               -146.8923    812.8708
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    diff = mean(control) - mean(experime)                         t =   1.3601
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.9131         Pr(|T| > |t|) = 0.1738          Pr(T > t) = 0.0 869
