👉 The Chi-square (χ²) is a statistical test used to determine if there is a significant association between two categorical variables or to assess how well observed data fit an expected distribution. It measures the difference between observed frequencies and expected frequencies under the assumption of independence. The χ² statistic is calculated by summing the squared differences between observed and expected values, divided by the expected values, and then compared to a chi-square distribution with a specific degrees of freedom. A high χ² value indicates a strong deviation from the expected distribution, suggesting that the variables are likely associated or that the observed data do not fit the expected pattern. This test is widely used in fields like social sciences, biology, and market research to analyze categorical data and infer relationships or patterns.
