Why Most Published Research Findings Are False

Posted by Chris Parker | August 30, 2005 1

John P. A. Ioannidis

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.

John P. A. Ioannidis is in the Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece, and Institute for Clinical Research and Health Policy Studies, Department of Medicine, Tufts-New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts, United States of America. E-mail: jioannid@cc.uoi.gr

Competing Interests: The author has declared that no competing interests exist.

Published: August 30, 2005

If Interested in Reading this Article (that’s unlikely, we know) Click Here

One Response

  • Thesprotos

    Dr. JPA Ioannidis is one of my teachersin Epidemiology. I’m a student at the medical School in Ioannina, Greece. Try to read this article of Dr. JPA Ioannidis which from i asume he had the idea to finaly complete the above article.
    “Contradicted and Initially Stronger Effects in Highly Cited Clinical Research” JAMA, July 13, 2005 – Vol 294, No 2

    consider that science makes it’s way with small steps even not so stable.

Leave a Reply

You must be logged in to post a comment.