The Confidence Interval of a Proportion. The lower and upper limits of the 95% confidence interval for a proportion, calculated according to two methods. The Confidence Interval for the Difference Between Two Independent Proportions. The lower and upper limits of the 95% confidence interval for the difference between two independent proportions, calculated according to two methods. Significance of the Difference Between Two Independent Proportions. Calculates the z-ratio and associated one-tail and two-tail probabilities for the difference between two independent proportions. McNemar's Test for Correlated Proportions in the Marginals of a 2x2 Contingency Table. Assesses the significance of the difference between two correlated proportions, such as might be found in the case where the two proportions are based on the same sample of subjects or on matched-pair samples.