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Mathematics

Chi-Square Tests: Goodness of Fit and Independence

Quick fact

The chi-square statistic is computed by summing (observed - expected)² / expected across all categories. Its distribution is defined by degrees of freedom, and it can be used for both goodness-of-fit and tests of independence.

Why this is interesting

Have you ever wondered if your favorite cereal brand really has more marshmallows than the others? Chi-square tests can tell you if such differences are just random or actually meaningful.