Evidence-based assessment (EBA) integrates three domains: (1) the best available research evidence on diagnostic test characteristics and clinical prediction rules, (2) the NP's clinical expertise and pattern recognition, and (3) the individual patient's clinical presentation, preferences, and circumstances. The foundation of EBA is DIAGNOSTIC REASONING -- the systematic process of generating, testing, and refining diagnostic hypotheses through targeted history, physical examination, and investigation. Two cognitive systems drive diagnostic reasoning: System 1 (intuitive, pattern-based, fast) recognizes familiar illness scripts instantly (e.g., chest pain + diaphoresis + ST elevation = STEMI), while System 2 (analytical, deliberate, slow) works through differential diagnoses systematically using hypothetico-deductive reasoning. Expert clinicians seamlessly integrate both systems but must recognize when System 1 pattern recognition fails (atypical presentations, unfamiliar conditions, cognitive biases). DIAGNOSTIC TEST INTERPRETATION requires understanding key statistical concepts: SENSITIVITY (true positive rate) -- a sensitive test, when negative, rules OUT the disease (SnNOut: Sensitivity, Negative, rule Out); SPECIFICITY (true positive rate among non-diseased) -- a specific test, when positive, rules IN the disease (SpPIn: Specificity, Positive, rule In); POSITIVE PREDICTIVE VALUE (PPV) -- probability of disease...