A nonparametric inferential statistical test based on the chi-square distribution. The chi-square test is frequently applied to determining the randomness of deviations between observed and expected values. Generally, the test is used to evaluate hypotheses dealing with the relationship between two categorical variables and “goodness of fit tests.” The chi-square test lacks the sensitivity of other available methods and is used primarily when the data can only be tabular in form. It is often reported in PDD literature, principally when comparing groups of test outcomes.