
Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 control |  17,281    21919.22    174.6134    22954.19    21576.96    22261.48
experime |  17,281    21729.02    171.6268    22561.58    21392.61    22065.43
---------+--------------------------------------------------------------------
combined |  34,562    21824.12    122.4182     22758.6    21584.18    22064.06
---------+--------------------------------------------------------------------
    diff |             190.201    244.8379               -289.6892    670.0912
------------------------------------------------------------------------------
    diff = mean(control) - mean(experime)                         t =   0.7768
Ho: diff = 0                                     degrees of freedom =    34560

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.7814         Pr(|T| > |t|) = 0.4373          Pr(T > t) = 0.2186
