Test-Treatment Threshold Simulator (2D)

Ordering a diagnostic test is itself a decision, and clinical decision analysis gives it exact math. This simulator renders the Pauker-Kassirer probability axis as a 2D threshold bar: drag a patient's pretest probability of disease along it, tune the test's sensitivity and specificity (or drag its point directly on the Se/Sp square) and the relative benefit/harm of treatment, and watch two computed thresholds split the bar into three zones — skip the work-up, order the test, or treat empirically without testing. A pair of bar-chart readouts show where a positive or a negative result would carry the patient's probability, so you can see directly whether the test result could plausibly change what you'd do next.