Two-way table

A two-way table, also called a contingency table, cross-classifies each individual by two categorical variables to show where the categories overlap. Row and column totals, called marginal totals, let you compute conditional and joint proportions to compare groups. For example, a table of 100 students by grade level in rows and whether they play a sport in columns reveals the sport rate within each grade. Such a table is the input to a chi-square test of independence or homogeneity, through its expected counts.