Copy of Significance, Confidence & Critical Values
Move the slider to choose a different significance level.
Notice how the confidence and the critical values change
along with the significance level.
The critical value, z alpha over 2, is the standard score
that separates an area of alpha over 2 in the right tail
from the rest of the distribution.
Since there are only a small number of values that are
typically used for the significance or the confidence,
the corresponding critical values can be memorized
fairly easily.