Introduction to Chi-Squared Test

Chi-Square Test is to test hypotheses about the relationship between two categorical variables.

Let's say you want to know if there is any difference in terms of effectiveness between wearing mask and not wearing mask. We have a variable of 'Infection' whose values would be 'Infected' or 'Not Infected' and a variable of 'Wearing Mask' whose values would be 'Yes' and 'No'. Are there any relationship between these two variables?

That's the kind of question we can use Chi-Square Test to answer.