A measure of 2 x 2 association with stable variance and approximately normal small-sample distribution: planning...

A measure of 2 x 2 association, Z, is developed having the property that n(Z - Z) has approximately a standard normal distribution, even for quite small sample size. Examples of the use of this variance-stabilizing and normalizing transformation in planning studies of 2 x 2 association are presented. Studies of the association between coronary artery disease and exercise stress test results are used to illustrate these methods.