This Cochran Armitage Trend tests for trends in binomial proportions across the levels of a single variable. This test is appropriate only when one variable has two levels and the other variable is ordinal. The two-level variable represents the response, and the other represents an explanatory variable with ordered levels. The null hypothesis is the hypothesis of no trend, which means that the binomial proportion is the same for all levels of the explanatory variable.
The test statistic and p-values given in this section are approximate. An exact version of the trend test is available. See Exact Test.