A contingency table is a display of data in columns and rows, arranged to facilitate the discovery of any relationship that may exist between different sets of data. The simplest type of contingency table displays two sets of data, one each in the columns and rows. The simplest of all is a fourfold, or 2 × 2, table. More complex contingency tables can be constructed with a further subclassification of data in the columns or rows, or in both columns and rows. Many varieties of data exist that can be arranged in this sort of table.
Some of the common variables that contingency tables show are: dichotomous (either-or); nominal (i.e. unordered, qualitative, classes, races); and ordinal (i.e. arranged along a scale that may or
JOHN M. LAST