USMLE purpose: Capture the short-form biostats teaching point as a rapid recall card for quick review.
For biostats shorts, treat the page like an Anki card: identify the clue, recall the formula, then check the answer.
A stem asks for “probability that a positive test is truly disease.” What is the metric?
| Clue | Metric |
|---|---|
| Positive test → disease? | PPV |
| Negative test → no disease? | NPV |
| Disease → test positive? | Sensitivity |
| No disease → test negative? | Specificity |