If we want to test for differences between two populations of nominal data with exactly two categories,we can employ either the z-test of p₁ − p₂,or the chi-squared test of a contingency table.

Z-Test

This is a statistical test used to determine whether two population means are different when the variances are known and the sample size is large.

Chi-Squared Test

A statistical method applied to ascertain whether a meaningful relationship exists between two variables of categorical nature.

Nominal Data

Data categorized into distinctly named groups without any natural order or ranking among them.