chi-square test
methods
correlation
a variant of Pearson's correlation applied to two variables each of which takes one of two values which may be coded 1 or 2 (or any other pair of values for that matter). As such, its most common applications are in correlating two items on a questionnaire where the answers are coded yes or no (or as some other binary alternatives), and in circumstances in which a 2 x 2 chi-square would alternatively be employed. [Source: The SAGE Dictionary of Statistics; phi coefficient]
phi coefficient