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| "There is increasing concern that in modern research, false findings may be the
majority or even the vast majority of published research claims," says
researcher John Ioannidis in an analysis in the open access international
medical journal PLoS Medicine.
In his analysis, Ioannidis, of the university of Ioannina School of Medicine,
Greece, and Tufts university School of Medicine, United States, identifies the
factors that he believes lead to research findings often being false.
One of these factors is that many research studies are small. "The smaller the
studies conducted in a scientific field, the less likely the research findings
are to be true," says Ioannidis.
Another problem is that in many scientific fields, the "effect sizes" (a measure
of how much a risk factor such as smoking increases a person's risk of disease,
or how much a treatment is likely to improve a disease) are small.
Research findings are more likely true in scientific fields with large effects,
such as the impact of smoking on cancer, than in scientific fields where
postulated effects are small, such as genetic risk factors for diseases where
many different genes are involved in causation. If the effect sizes are very
small in a particular field, says Ioannidis, it is "likely to be plagued by
almost ubiquitous false positive claims."
Financial and other interests and prejudices can also lead to untrue results.
And "the hotter a scientific field (with more scientific teams involved), the
less likely the research findings are to be true," which may explain why we
sometimes see "major excitement followed rapidly by severe disappointments in
fields that draw wide attention."
In their linked editorial, the PLoS Medicine editors discuss the implications of
Ioannidis' analysis. "Publication of preliminary findings, negative studies,
confirmations, and refutations is an essential part of getting closer to the
truth," they say.
Nevertheless, the editors "encourage authors to discuss biases, study
limitations, and potential confounding factors. We acknowledge that most studies
published should be viewed as hypothesis-generating, rather than conclusive."
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Citation: Ioannidis JPA (2005) Why most published research findings are false.
PLoS Med 2(8): e124.
About PLoS Medicine
PLoS Medicine is an open access, freely available international medical journal.
It publishes original research that enhances our understanding of human health
and disease, together with commentary and analysis of important global health
issues. For more information, visit http://www.plosmedicine.org
About the Public Library of Science
The Public Library of Science (PLoS) is a non-profit organization of scientists
and physicians committed to making the world's scientific and medical literature
a freely available public resource. For more information, visit
http://www.plos.org
Alan
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