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Confidence, Significance and Critical Values

Move the slider to choose a different significance level.
Notice how the confidence and the critical values change
as the significance level increases and decreases.

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The critical value, z subscript α/2, is the standard score
that separates an area of α/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,
memorizing the corresponding critical values is easier
than computing them every time.

David Gurney, Created with GeoGebra