Aggregating multiple test results to improve medical decision-making
Fig 2
The ratio of the number of parallel tests to the number of series tests necessary to determine the aggregated output from n = 2 tests as a function of prevalence f.
Results in panels (A) and (B) are based on AND and OR aggregations of two tests, using Eqs (11) and (12), respectively. We consider three different combinations of true positive and true negative rates (solid black lines: TNR1 = 0.95 and TNR1 = 0.95; dashed red lines: TNR1 = 0.90 and TNR1 = 0.95; dash-dotted blue lines: TNR1 = 0.95 and TNR1 = 0.90). The critical values fc for which the ratios in panel (A) are larger than the ratios in panel (B) are given, respectively, by fc = 0.50, 0.47, 0.53. For f < fc greater savings are achieved by utilizing the AND-aggregated series tests, compared to the OR-aggregated series test.