USMLE purpose: Interpret effect size and drug-ad statistics without getting distracted by abstract formatting.

How to use this page

  1. Identify the outcome and comparator.
  2. Check the point estimate and confidence interval.
  3. Ask whether the CI crosses the no-effect value.
  4. Translate effect size into clinical meaning.

One-liner

Drug-ad questions usually test whether the result is statistically significant, clinically meaningful, and supported by the actual data.

Drug-ad interpretation table

Data shown No-effect value Significance rule
Relative risk / odds ratio / hazard ratio 1 CI crossing 1 = not significant
Mean difference 0 CI crossing 0 = not significant
P value 0.05 p < 0.05 usually significant
NNT Lower is usually stronger NNT = 1 / ARR

Board-style decision workflow

  1. Identify the statistic: RR/OR/HR, mean difference, p value, ARR, or NNT.
  2. Check the no-effect value: 1 for ratios, 0 for differences.
  3. Check statistical significance: CI must not cross the no-effect value.
  4. Check clinical meaning: statistically significant does not always mean clinically meaningful.

Anki-style rapid recall