a statistical procedure to determine whether two categorical variables are related. Appropriate for small samples, it examines the associations between the rows and columns of data in a fourfold (2 × 2) contingency table. For example, the Fisher exact test could be used to assess whether there is a relationship between gender (male or female) and pizza topping preference (cheese or multitopping) in a group of 20 individuals. [Ronald Aylmer Fisher]