Chi-Square

Also known as: Chi-square Test, Pearson's Chi-square, Independence Test

Statistical test evaluating whether there is a significant association between two categorical variables in a contingency table.

The Chi-Square (χ²) Test is a non-parametric statistical test that evaluates whether there is a statistically significant association between two nominal categorical variables in a contingency table (e.g., Is brand preference related to socioeconomic level?).

It works by comparing the frequencies observed in each cell of the table against the expected frequencies under the null hypothesis of independence. If the difference is large enough (p < 0.05), the independence hypothesis is rejected and it is concluded that the variables are related.

It is one of the most used tests in survey crosstab analysis. However, it only indicates whether an association exists, not its direction or magnitude—for that, association measures such as Cramér's V or odds ratios are used.