On the Principles of Believe the Positive and Believe the Negative for Diagnosis Using Two Continuous Tests

by Changyu Shen

Journal of Data Science, v.6, no.2, 189-205

Abstract

Believe the Positive (BP) and Believe the Negative (BN) rules for combining two continuous diagnostic tests are compared with procedures based on likelihood ratio and linear combination of the two tests. The sensitivity-specificity relationship for BP/BN is illustrated through a graphical presentation of a "ROC surface", which leads to a natural approach of choosing between BP and BN. With a bivariate normal model, it is shown that the discriminating power of this approach is higher when the correlation between the two tests has different signs for non-diseased and diseased population, given the location and variations of the two distributions are fixed. The idea is illustrated through an example.

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