On tests for equality of predictive values for t diagnostic procedures.

This paper concerns comparisons of the efficiency of several diagnostic tests, as characterized by the measures of sensitivity (xi), specificity (eta) and predictive value (rho). We show that hypotheses concerning the equality of predictive values relate only to hypotheses concerning xi and eta and that we can test these by approximate chi 2 statistics. Data for the cases of t = 2 or 3 diagnostic tests illustrate the method.