Research, Evidence, and Education
What the exam expects
Understand study designs (RCT, cohort, case-control, cross-sectional, systematic review), levels of evidence, and basic biostatistics: sensitivity, specificity, PPV/NPV, likelihood ratios, confidence intervals, p-values, and measures of effect. Know how to appraise validity, applicability, and bias. Understand evidence-based practice as integrating best evidence, clinical expertise, and patient values, and how to educate patients and learners effectively.
Traps
Questions test misinterpretation of p-values (not the probability the hypothesis is true) and confidence intervals (overlap indicating non-significance). A common trap is confusing PPV/NPV (which depend on prevalence) with sensitivity/specificity (which do not). Another is overgeneralizing study results beyond the population studied. Watch for equating statistical significance with clinical importance.
Rule of thumb
Sensitivity and specificity are properties of the test; PPV and NPV shift with prevalence-so a positive test means more in a high-prevalence setting.
Worked example
A test with 90% sensitivity and 90% specificity used in a low-prevalence population yields many false positives, lowering PPV. Interpret a positive result cautiously when prevalence is low.