Explain how to perform a two-sample z-test for the difference between two population proportions.

Point estimate for the difference between two population proportions is the difference between the two sample proportions, written as:



and the standard deviation is given by



When np and n(1-p) is greater than 5, then the sampling distribution is approximately normal and we can use standard normal methods.

Thus, the propability of a test for the difference between two population proportions is given by