Rejecting or Failing to reject the Null Hypothesis (Ho) depends
of the P-Value. Generally, the P-value (probability( Observation |
Ho ) ) is around .05, thus minimizing the Type 1 error rate. If the
P-value < Alpha , you would reject the Ho, and instead believe
the Ha (Alternative Hypothesis), and if the P-value > Alpha, you
would Fail to reject the Ho because there is not enough evidence to
believe the Ha.