
Two-sample t test with equal variances
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   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    22009.04    176.0501    23143.06    21663.96    22354.11
experime |  17,281     21639.2    170.1441    22366.67     21305.7     21972.7
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |            369.8348    244.8319               -110.0438    849.7133
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    diff = mean(control) - mean(experime)                         t =   1.5106
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.9345         Pr(|T| > |t|) = 0.1309          Pr(T > t) = 0.0655
