
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281     21996.4     174.884    22989.76    21653.61    22339.19
experime |  17,281    21651.84    171.3441    22524.41    21315.99    21987.69
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            344.5575     244.833               -135.3231    824.4382
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    diff = mean(control) - mean(experime)                         t =   1.4073
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.9203         Pr(|T| > |t|) = 0.1593          Pr(T > t) = 0.0 797
