ZIP Code Demographics is a process that provides statistics and characteristics of a population located within a designated ZIP code area. The information provided includes attributes like ages, genders, ethnographic data, total population size, languages spoken, economic strata and others.

Z-test is a statistical test that is based on the standard normal distribution. Z-tests are useful while determining the inferences like statistical significance of the difference between sample means and the population means. The reliability of the Z-Tests is based on the knowledge of the population mean and population standard deviation in a simple random sample.