Biostatistics & Research · single question
A study reports three different laser treatments (A, B, C) with confidence intervals. Which laser should you select? CI A: 3.5 (-1.3 to 5.5), CI B: 3.5 (2.34 to 5.12), CI C: 3.xx (-1 to 6.8).
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Correct answer: D. Laser B — its CI does not include zero/1, indicating significance
Laser B is the correct choice because its confidence interval (2.34–5.12) does not include zero (or 1 for RR), indicating statistical significance. Lasers A and C both have CIs that cross zero/null (A: -1.3 to 5.5; C: -1 to 6.8), meaning the observed effect could be due to chance — they are NOT statistically significant. When choosing between interventions, select the one whose CI excludes the null value.
- A. ❌ Laser A's CI crosses zero (-1.3 to 5.5) — the result is not statistically significant; cannot recommend.
- B. ❌ Laser C's CI crosses zero (-1 to 6.8) — statistically insignificant; wider CI means less precision.
- C. ❌ All have the same point estimate of ~3.5, but only Laser B's CI excludes the null value.
- D. ✅ CORRECT – Laser B's CI (2.34 to 5.12) does not include zero, confirming statistical significance. Lasers A and C have CIs crossing zero → not significant.
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