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Why We Need Confidence Intervals

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Abstract

The estimation approach to statistical analysis aims to quantify the effect of interest as an “estimate” of a clinically relevant quantity and to quantify the uncertainty in this estimate by means of a confidence interval (CI). As such, results expressed in this form are much more informative than results presented just as p values. This article focuses on the principles rather than the mathematics of CIs and discusses interpretation of CIs and some common misuses. CIs can be constructed for almost all analyses. They are especially useful for avoiding misinterpretation of nonsignificant results of small studies. CIs should be provided routinely for the main results of trials and observational studies.

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References

  1. Altman, DG, Machin, D, Bryant, TN, et al. (2000), Statistics with Confidence, 2nd ed., BMJ Books, London, (including CIA software)

  2. Altman, DG (2000) “Confidence intervals” In: Sackett, DL, Straus, S, Richardson, WS (editors), Evidence-based Medicine: How to Practice and Teach EBM, 2nd ed., Churchill-Livingstone, Edinburgh, pp 233-243

  3. L Neumayer A Giobbie-Hurder O Jonasson et al. (2004) ArticleTitleOpen mesh versus laparoscopic mesh repair of inguinal hernia N. Engl. J. Med 350 1819–1827 Occurrence Handle10.1056/NEJMoa040093 Occurrence Handle15107485

    Article  PubMed  Google Scholar 

  4. KL Leung SP Kwok SC Lam et al. (2004) ArticleTitleLaparoscopic resection of rectosigmoid carcinoma: prospective randomized trial Lancet 363 1187–1192 Occurrence Handle10.1016/S0140-6736(04)15947-3 Occurrence Handle15081650

    Article  PubMed  Google Scholar 

  5. P Koivunen M Uhari J Luotonen et al. (2004) ArticleTitleAdenoidectomy versus chemoprophylaxis and placebo for recurrent acute otitis media in children aged under 2 years: randomized controlled trial B. M. J 328 487–490

    Google Scholar 

  6. DG Altman JM Bland (2004) ArticleTitleConfidence intervals illuminate absence of evidence B. M. J 328 1016–1017

    Google Scholar 

  7. J Widman H Jacobsson SA Larsson et al. (2002) ArticleTitleNo effect of drains on the postoperative hematoma volume in hip replacement surgery: a randomized study using scintigraphy Acta. Orthop. Scand 73 625–629 Occurrence Handle10.1080/000164702321039570 Occurrence Handle12553508

    Article  PubMed  Google Scholar 

  8. Altman, DG, Bland, JM (1995) “Absence of evidence is not evidence of absence” B.M.J. 311: 485

    Google Scholar 

  9. P Alderson (2004) ArticleTitleAbsence of evidence is not evidence of absence B. M. J 328 476–477

    Google Scholar 

  10. DG Altman JM Bland (2003) ArticleTitleInteraction revisited: the difference between two estimates B. M. J 326 219

    Google Scholar 

  11. D Moher KF Schulz DG Altman et al. (2001) ArticleTitleThe CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomised trials Lancet 357 1191–1194 Occurrence Handle10.1016/S0140-6736(00)04337-3 Occurrence Handle11323066

    Article  PubMed  Google Scholar 

  12. HR Vikram J Buenconsejo R Hasbun et al. (2003) ArticleTitleImpact of valve surgery on 6-month mortality in adults with complicated, left-sided native valve endocarditis: a propensity analysis J. A. M. A 290 3207–3214 Occurrence Handle14693873

    PubMed  Google Scholar 

  13. DP Taggart R D’Amico DG Altman (2001) ArticleTitleEffect of arterial revascularisation on survival: a systematic review of studies comparing bilateral and single internal mammary arteries Lancet 358 870–875 Occurrence Handle10.1016/S0140-6736(01)06069-X Occurrence Handle11567701

    Article  PubMed  Google Scholar 

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Correspondence to Douglas G. Altman DSc.

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Altman, D.G. Why We Need Confidence Intervals. World J. Surg. 29, 554–556 (2005). https://doi.org/10.1007/s00268-005-7911-0

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