Journal article: 50%+ of science journal articles have false conclusions

In an article in the Public Library of Science Medicine, John P. A. Ioannidis, an epidemiologist, argues that more than 50 percent of the conclusions drawn in papers published in scientific journals are false. The money sentence is this one: "The replication process is more important than the first discovery." The popular culture version of science is about labcoats and discovery, the real world science is about publishing, review and replication.
"We should accept that most research findings will be refuted. Some will be replicated and validated. 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. If you test 20 false hypotheses, one of them is likely to show up as true, on average.