Cited by 3,200Statistics Education and MethodologiesStatistical Methods in EpidemiologyMeta-analysis and systematic reviews

Statistical tests, P values, confidence intervals, and power: a guide to misinterpretations

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Greenland, Sander, Senn, Stephen J., Rothman, Kenneth J., Carlin, John B., Poole, Charles, Goodman, Steven N., Altman, Douglas G.·2016·European Journal of Epidemiology

Abstract

Misinterpretation and abuse of statistical tests, confidence intervals, and statistical power have been decried for decades, yet remain rampant. A key problem is that there are no interpretations of these concepts that are at once simple, intuitive, correct, and foolproof. Instead, correct use and interpretation of these statistics requires an attention to detail which seems to tax the patience of working scientists. This high cognitive demand has led to an epidemic of shortcut definitions and interpretations that are simply wrong, sometimes disastrously so-and yet these misinterpretations dominate much of the scientific literature. In light of this problem, we provide definitions and a discussion of basic statistics that are more general and critical than typically found in traditional introductory expositions. Our goal is to provide a resource for instructors, researchers, and consumers of statistics whose knowledge of statistical theory and technique may be limited but who wish to avoid and spot misinterpretations. We emphasize how violation of often unstated analysis protocols (such as selecting analyses for presentation based on the P values they produce) can lead to small P values even if the declared test hypothesis is correct, and can lead to large P values even if that hypothesis is incorrect. We then provide an explanatory list of 25 misinterpretations of P values, confidence intervals, and power. We conclude with guidelines for improving statistical interpretation and reporting.

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  1. [3]Ashworth A. Veto on the use of null hypothesis testing and p intervals: right or wrong? Taylor & Francis Editor. 2015. Resources online, http://editorresources.taylorandfrancisgroup.com/veto-on-the-use-of-null-hypothesis-testing-and-p-intervals-right-or-wrong/. Accessed 27 Feb 2016.
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Authors
Greenland, S., Senn, S. J., Rothman, K. J., Carlin, J. B., Poole, C., Goodman, S. N., & Altman, D. G.
Affiliations
  • University of California, Los Angeles (US)
  • Luxembourg Institute of Health (LU)
  • RTI International (US)
  • The University of Melbourne (AU)
  • University of North Carolina at Chapel Hill (US)
  • Stanford Medicine (US)
  • University of Oxford (GB)
Corresponding author
Greenland, Sander
Venue
European Journal of Epidemiology
Published
2016-04
Volume
31
Issue
4
Pages
337-350
ISSN
  • 0393-2990 (ISSN-L)
  • 1573-7284
OpenAlex
W2408017125
Cited by
3,200
References
135
Citations by year
2026: 325 · 2025: 454 · 2024: 407 · 2023: 290 · 2022: 348 · 2021: 392 · 2020: 330 · 2019: 270 · 2018: 201 · 2017: 148 · 2016: 33 · 2015: 1
FWCI
220.87
Type
journal article
Language
en
Open access
Locations
  • European Journal of Epidemiology (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • eScholarship (California Digital Library) (submittedVersion, cc-by)
  • Minerva Access (University of Melbourne) (submittedVersion, cc-by)
Funders
Seventh Framework Programme (602552)
Topics
  • Physical Sciences › Mathematics › Statistics and Probability › Statistics Education and Methodologies
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
Keywords
p-values, confidence intervals, statistical power, statistical misinterpretation, hypothesis testing, selective analysis, analysis protocol, statistical reporting guidelines, statistics education
MeSH terms
Data Interpretation, Statistical, Humans, Probability, Confidence Intervals

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