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Implications of overviews of randomized trials
Author(s) -
Hennekens Charles H.,
Buring Julie E.,
Hebert Patricia R.
Publication year - 1987
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4780060337
Subject(s) - sample size determination , randomized controlled trial , null hypothesis , statistical power , treatment effect , randomized experiment , research design , sample (material) , computer science , medicine , psychology , econometrics , statistics , economics , mathematics , chemistry , surgery , chromatography , traditional medicine , pathology
Abstract Many randomized trials are of insufficient sample size to detect with adequate power the small to moderate effects that are most likely to occur. As a result, a single such trial can produce a null rinding that is, in fact, uninformative, but none the less is misinterpreted as demonstrating no effect. An overview considers all available trials and can increase the statistical power to detect an effect if present. Thus overviews can provide perhaps the most precise estimate of the magnitude of a treatment effect based on existing data. This may have implications for the formulation of public policy but certainly should influence the conduct and planning of randomized trials. Public policy may be influenced in circumstances where further trials are unlikely to be conducted. Overviews can also provide guidance as to whether changes in protocols of ongoing studies are recommended as a result of new evidence. Perhaps most importantly, overviews can provide information about whether additional trials are warranted, and, if so, the sample size that would be required to answer the research question definitively.