
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21837.04    170.9382    22471.06    21501.99     22172.1
experime |  17,281     21811.2    175.2905     23043.2    21467.61    22154.79
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            25.84362      244.84               -454.0507    505.7379
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    diff = mean(control) - mean(experime)                         t =   0.1056
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.5420         Pr(|T| > |t|) = 0.9159          Pr(T > t) = 0.4580
