Why Most Published Research Findings Are False
John P. A. Ioannidis
Ioannidis JPA (2005) Why Most Published Research Findings Are False.
PLoS Med 2(8): e124

Summary

There is increasing concern that most current published research
findings are false. The probability that a research claim is true may
depend on study power and bias, the number of other studies on the
same question, and, importantly, the ratio of true to no relationships
among the relationships probed in each scientific field. In this
framework, a research finding is less likely to be true when the
studies conducted in a field are smaller; when effect sizes are
smaller; when there is a greater number and lesser preselection of
tested relationships; where there is greater flexibility in designs,
definitions, outcomes, and analytical modes; when there is greater
financial and other interest and prejudice; and when more teams are
involved in a scientific field in chase of statistical significance.
Simulations show that for most study designs and settings, it is more
likely for a research claim to be false than true. Moreover, for many
current scientific fields, claimed research findings may often be
simply accurate measures of the prevailing bias. In this essay, I
discuss the implications of these problems for the conduct and
interpretation of research.
Full text:
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urnal.pmed.0020124