**Chi-squared test (September 3, 1999)**

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*Dear Professor Mean, Can the Chi-square test be used for anything besides categorical data?*

The Chi-square test exists in many different forms. It is useful for testing

whether a categorical variable conforms to a set of hypothesized probabilities. It can also testwhether two categorical variables are independent. Both of these tests involve comparing expected counts to observed counts.There is also a Chi-square test for examining

whether a sample variance is equal to a hypothesized value. For this test, you look at the ratio of the sample variance to the hypothesized variance.Finally

many nonparametric tests rely on the Chi-square distribution as an approximationwhen you don't have exact tables available.