Chi Square Test — Intuition, Examples, and Step-by-Step Calculation

The best way to see if two variables are related

You’ve probably heard of the term “Chi square test” at least once in your life if you have ever studied for the SAT, or worked in some science-related field. Chi-square test is used a lot in corporations, especially when making decisions involving, for instance, medical, product design, engineering, and nearly all research projects.

For you to understand what the chi square test is, you need to first know what hypothesis testing is. Because the chi square test is one type of hypothesis test. I know it’s a little frustrating to have to know all these previous concepts before even talking about the chi-square test, but it’s impossible to learn math concepts without first understanding what came before them. But once you know what hypothesis testing is, you will be able to build on that foundation to understand many different kinds of hypothesis testing, for example, chi-square test, t-test, Z test, Wilcoxon’s test, etc.

I think all these fancy terms (e.g. null/alternative hypothesis, type 1 error, type 2 error, degrees of freedom, p-values, etc.) make the chi square test sound a lot more complicated than it is. But the basic idea of hypothesis testing is quite simple and straightforward.

What is Hypothesis Testing?

Hypothesis testing is a statistical analysis that looks at samples and sees if the…