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Progressive Statistics for Studies in Sports Medicine and Exercise Science

HOPKINS, WILLIAM G.1; MARSHALL, STEPHEN W.2; BATTERHAM, ALAN M.3; HANIN, JURI4

Medicine & Science in Sports & Exercise: January 2009 - Volume 41 - Issue 1 - pp 3-12
doi: 10.1249/MSS.0b013e31818cb278
Editorial

Statistical guidelines and expert statements are now available to assist in the analysis and reporting of studies in some biomedical disciplines. We present here a more progressive resource for sample-based studies, meta-analyses, and case studies in sports medicine and exercise science. We offer forthright advice on the following controversial or novel issues: using precision of estimation for inferences about population effects in preference to null-hypothesis testing, which is inadequate for assessing clinical or practical importance; justifying sample size via acceptable precision or confidence for clinical decisions rather than via adequate power for statistical significance; showing SD rather than SEM, to better communicate the magnitude of differences in means and nonuniformity of error; avoiding purely nonparametric analyses, which cannot provide inferences about magnitude and are unnecessary; using regression statistics in validity studies, in preference to the impractical and biased limits of agreement; making greater use of qualitative methods to enrich sample-based quantitative projects; and seeking ethics approval for public access to the depersonalized raw data of a study, to address the need for more scrutiny of research and better meta-analyses. Advice on less contentious issues includes the following: using covariates in linear models to adjust for confounders, to account for individual differences, and to identify potential mechanisms of an effect; using log transformation to deal with nonuniformity of effects and error; identifying and deleting outliers; presenting descriptive, effect, and inferential statistics in appropriate formats; and contending with bias arising from problems with sampling, assignment, blinding, measurement error, and researchers' prejudices. This article should advance the field by stimulating debate, promoting innovative approaches, and serving as a useful checklist for authors, reviewers, and editors.

1Institute of Sport and Recreation Research, AUT University, Auckland, NEW ZEALAND; 2Departments of Epidemiology, Orthopedics, and Exercise & Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC; 3School of Health and Social Care, University of Teesside, Middlesbrough, UNITED KINGDOM; and 4KIHU-Research Institute for Olympic Sports, Jyvaskyla, FINLAND

Address for correspondence: Will G. Hopkins, Ph.D., FACSM, Institute of Sport and Recreation Research, AUT University, Akoranga Drive, Private Bag 92006, Auckland 0627, New Zealand; E-mail: will@clear.net.nz.

Submitted for publication July 2008.

Accepted for publication September 2008.

© 2009 American College of Sports Medicine