The new analysis, called the Reproducibility Project, found no evidence of fraud or that any original study was definitively false. Rather, it concluded that the evidence for most published findings was not nearly as strong as originally claimed.

Dr. John Ioannidis, a director of Stanford University’s Meta-Research Innovation Center, who once estimated that about half of published results across medicine were inflated or wrong, noted the proportion in psychology was even larger than he had thought. He said the problem could be even worse in other fields, including cell biology, economics, neuroscience, clinical medicine, and animal research.

The report appears at a time when the number of retractions of published papers is rising sharply in a wide variety of disciplines. Scientists have pointed to a hypercompetitive culture across science that favors novel, sexy results and provides little incentive for researchers to replicate the findings of others, or for journals to publish studies that fail to find a splashy result.

“We see this is a call to action, both to the research community to do more replication, and to funders and journals to address the dysfunctional incentives,” said Brian Nosek, a psychology professor at the University of Virginia and executive director of the Center for Open Science, the nonprofit data-sharing service that coordinated the project published Thursday, in part with $250,000 from the Laura and John Arnold Foundation. The center has begun an effort to evaluate widely cited results in cancer biology, and experts said that the project could be adapted to check findings in many sciences.

In a conference call with reporters, Marcia McNutt, the editor in chief of Science, said, “I caution that this study should not be regarded as the last word on reproducibility but rather a beginning.” In May, after two graduate students raised questions about the data in a widely reported study on how political canvassing affects opinions of same-sex marriage, Science retracted the paper.

The new analysis focused on studies published in three of psychology’s top journals: Psychological Science, the Journal of Personality and Social Psychology, and the Journal of Experimental Psychology: Learning, Memory, and Cognition.

The act of double-checking another scientist’s work has been divisive. Many senior researchers resent the idea that an outsider, typically a younger scientist, with less expertise, would critique work that often has taken years of study to pull off.