phi coefficient
(symbol: φ) a measure of association for two dichotomous or binary random variables. The phi coefficient is the product-moment correlation coefficient when both variables are coded (0, 1). For example, the phi coefficient could be used to examine the relationship between gender (male [0] and female [1]) and left- (0) or right-handedness (1). A table could be constructed to record the frequency of people with a 0 on both variables (i.e., left-handed males), a 1 on both variables (i.e., right-handed females), a 0 on the first variable and a 1 on the other (i.e., right-handed males), and vice versa (i.e., left-handed females). The pairs of responses on the variables could then be analyzed and a phi coefficient calculated to determine whether any relationship exists. See also Cramér’s V; tetrachoric correlation coefficient.