Originally published September 23 2005
Half of all scientific studies produce false conclusions
by Mike Adams, the Health Ranger, NaturalNews Editor
If the latest study by researchers at the University of Loannina School of Medicine in Greece is correct, most scientific studies are wrong because of small sample sizes, poor study design, researcher bias, selective reporting and other problems, New Scientist reports.
Assuming that the new paper is itself correct, problems with experimental and statistical methods mean that there is less than a 50% chance that the results of any randomly chosen scientific paper are true.
John Ioannidis, an epidemiologist at the University of Ioannina School of Medicine in Greece, says that small sample sizes, poor study design, researcher bias, and selective reporting and other problems combine to make most research findings false.
The replication process is more important than the first discovery," Ioannidis says.
Traditionally a study is said to be "statistically significant" if the odds are only 1 in 20 that the result could be pure chance.
But in a complicated field where there are many potential hypotheses to sift through - such as whether a particular gene influences a particular disease - it is easy to reach false conclusions using this standard.
Odds get even worse for studies that are too small, studies that find small effects (for example, a drug that works for only 10% of patients), or studies where the protocol and endpoints are poorly defined, allowing researchers to massage their conclusions after the fact.
Surprisingly, Ioannidis says another predictor of false findings is if a field is "hot", with many teams feeling pressure to beat the others to statistically significant findings.
But Solomon Snyder, senior editor at the Proceedings of the National Academy of Sciences, and a neuroscientist at Johns Hopkins Medical School in Baltimore, US, says most working scientists understand the limitations of published research.
"When I read the literature, I'm not reading it to find proof like a textbook.
So even if something is wrong with the paper, if they have the kernel of a novel idea, that's something to think about," he says.
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