Doping experts have long known that drug tests catch only a tiny fraction of the athletes who use banned substances because athletes are constantly finding new drugs and techniques to evade detection. So in 2011, the World Anti-Doping Agency convened a team of researchers to try to determine more accurately how many athletes use performance-enhancing drugs.

More than 2,000 track and field athletes participated in the study, and according to the findings, which were reviewed by The New York Times, an estimated 29 percent of the athletes at the 2011 world championships and 45 percent of the athletes at the 2011 Pan-Arab Games said in anonymous surveys that they had doped in the past year.

By contrast, less than 2 percent of drug tests examined by WADA laboratories in 2010 were positive.

The researchers were eager to publish their results, which they believed would expose a harsh reality of modern sports: that far more athletes are doping than might be imagined, and that current drug-testing protocols catch few of the cheaters. But after a final draft of the study was submitted to the antidoping agency, the organization ultimately told the researchers they could not publish their findings at this time, according to three of the researchers, who requested anonymity because they signed nondisclosure agreements with the agency. The agency said track and field’s world governing body needed to review the findings first, the researchers said.

“It was going to be a really sensitive issue, and they needed time to figure out how to deal with it,” one of the researchers said. “What was going to be the international response?”