A critical value (C.V.) is a number that is used to make estimates and test hypotheses. Critical values always correspond to a probability.
This number represents the distance from itself to the center of a bell-shaped graph, either the z or t distribution. The area in this section represents the probability of the C.V.
For example, using the z distribution, the number 1.96 is 47.5% likely. When you also include -1.96, then the likelihood is doubled.
Alpha and Confidence Level are probabilities that correspond to critical values.
