USMLE purpose: Rapid-review a single biostats shortcut in Anki-card style.

How to use this page

1. Identify whether the question is about disease status or test result.
2. Choose sensitivity/specificity vs PPV/NPV.
3. Open the toggle to confirm.

• Episode metadata

One-liner

If disease status is known first, think sensitivity/specificity; if test result is known first, think PPV/NPV.

• Disease present → test positive?
• Test positive → disease present?

Extra practice

A question says, “Among patients with disease, how many test positive?” Which metric is this?

• Reveal answer & explanation