A critical value is used in significance testing. It is the value that a test statistic must exceed in order for the the null hypothesis to be rejected. For example, the critical value of t (with 12 degrees of freedom using the 0.05 significance level) is 2.18. This means that for the probability value to be less than or equal to 0.05, the absolute value of the t statistic must be 2.18 or greater. It should be noted that the all-or-none rejection of a null hypothesis is not recommended.

It should be noted that the all-or-none rejection of a null hypothesis is not recommended.