Move the slider to choose a different significance level. [br]Notice how the confidence and the critical values change[br]along with the significance level.

The critical value, z alpha over 2, is the standard score [br]that separates an area of alpha over 2 in the right tail [br]from the rest of the distribution. [br][br]Since there are only a small number of values that are [br]typically used for the significance or the confidence,[br]the corresponding critical values can be memorized[br]fairly easily.