In testing the difference between two proportions using the normal distribution, we may use a two-tail Z test.

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A two-tail Z test is commonly used to test the difference between two proportions when the sample size is large enough and certain assumptions are met. It is called a two-tail test because we are testing if the difference between the proportions is not equal to zero in either direction (i.e. if it is significantly greater or smaller than zero).

In Testing the Difference Between Two Proportions Using the Normal