The chi-square test is the default choice for testing whether two categorical variables are related. But it relies on an approximation that breaks down when your sample is small. When one or more cells in your table have very low expected counts, the p-value chi-square gives you can be misleading. That is exactly when Fisher’s
When you have two categorical variables and want to see how they relate, a crosstab is usually the first table you should build. It shows the counts in every combination of categories, and with a few extra options switched on, it also tells you whether the pattern you see is bigger than chance. This tutorial
When do you need the chi-square test of independence? You have two categorical variables and one nagging question: are they related? Does beverage preference differ between men and women? Is smoking status associated with education level? Is defect type linked to the factory shift that produced it? Whenever both variables are categories — not numbers,