%0 Journal Article
%T Current sample size conventions: Flaws, harms, and alternatives
%A Peter Bacchetti
%J BMC Medicine
%D 2010
%I BioMed Central
%R 10.1186/1741-7015-8-17
%X This requirement and the methods for meeting it have severe flaws. Notably, the true nature of how sample size influences a study's projected scientific or practical value precludes any meaningful blanket designation of <80% power as "inadequate". In addition, standard calculations are inherently unreliable, and focusing only on power neglects a completed study's most important results: estimates and confidence intervals. Current conventions harm the research process in many ways: promoting misinterpretation of completed studies, eroding scientific integrity, giving reviewers arbitrary power, inhibiting innovation, perverting ethical standards, wasting effort, and wasting money. Medical research would benefit from alternative approaches, including established value of information methods, simple choices based on cost or feasibility that have recently been justified, sensitivity analyses that examine a meaningful array of possible findings, and following previous analogous studies. To promote more rational approaches, research training should cover the issues presented here, peer reviewers should be extremely careful before raising issues of "inadequate" sample size, and reports of completed studies should not discuss power.Common conventions and expectations concerning sample size are deeply flawed, cause serious harm to the research process, and should be replaced by more rational alternatives.Early in my career, an epidemiologist told me that dealing with sample size is the price one has to pay for being a biostatistician. Since then, I have spent untold time and effort paying this price, while also coming to realize that such effort produces no real scientific benefit. Unfortunately, widespread misconceptions about sample size hurt not only statisticians, but also the quality of medical science generally.The conventional expectation is that a study must have at least 80% power or else be considered scientifically unsound and even unethical [1]. Some challenges to
%U http://www.biomedcentral.com/1741-7015/8/17