BMJ  2004;328:1016-1017 (24 April), doi:10.1136/bmj.328.7446.1016-b

Letter

Confidence intervals illuminate absence of evidence

The first 150 words of the full text of this article appear below.

EDITOR—We agree with Alderson that authors should recognise that non-significant results are compatible with a range of possible findings.¹ Papers in the same issue of the BMJ do not adhere to this good advice.

Koivunen et al concluded that adenoidectomy is not effective and cannot be recommended, yet the 95% confidence interval for further episodes of otitis media is compatible with an 18% absolute risk reduction.² The clinically important difference sought was a 25% reduction.

Kariminia et al said that hands and knees exercise with pelvic rocking did not reduce the incidence of persistent occiput posterior position at birth³; the 95% confidence interval was from 1.8% reduction to 2.5% increased risk. This trial sought a risk reduction of 2.5%.

Marre et al concluded that "low dose ramipril has no effect on cardiovascular and renal outcomes"⁴—the 95% confidence interval was from 15% reduction to 11% increased risk. . . . [Full text of this article]

Cancer Research UK Medical Statistics Group, Centre for Statistics in Medicine, Oxford OX3 7LF doug.altman@cancer.org.uk

Department of Health Sciences, University of York, York YO10 5DD

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Relevant Articles

Absence of evidence is not evidence of absence

Phil Alderson
BMJ 2004 328: 476-477. [Extract] [Full Text] [PDF]

Randomised controlled trial of effect of hands and knees posturing on incidence of occiput posterior position at birth

Azar Kariminia, Marie E Chamberlain, John Keogh, and Agnes Shea
BMJ 2004 328: 490. [Abstract] [Full Text] [PDF]

Effects of low dose ramipril on cardiovascular and renal outcomes in patients with type 2 diabetes and raised excretion of urinary albumin: randomised, double blind, placebo controlled trial (the DIABHYCAR study)

Michel Marre, Michel Lievre, Gilles Chatellier, Johannes F E Mann, Philippe Passa, and Joël Ménard
BMJ 2004 328: 495. [Abstract] [Full Text] [PDF]

Adenoidectomy versus chemoprophylaxis and placebo for recurrent acute otitis media in children aged under 2 years: randomised controlled trial

Petri Koivunen, Matti Uhari, Jukka Luotonen, Aila Kristo, Risto Raski, Tytti Pokka, and Olli-Pekka Alho
BMJ 2004 328: 487. [Abstract] [Full Text] [PDF]

This article has been cited by other articles:

• Muller, M.J., Mazanek, M., Weibrich, C., Dellani, P.R., Stoeter, P., Fellgiebel, A. (2006). Distribution characteristics, reproducibility, and precision of region of interest-based hippocampal diffusion tensor imaging measures.. Am. J. Neuroradiol. 27: 440-446 [Abstract] [Full text]  
• Cummings, P., Rivara, F. P., Koepsell, T. D. (2004). Writing Informative Abstracts for Journal Articles. Arch Pediatr Adolesc Med 158: 1086-1088 [Full text]  

Online poll

Find out more >>