A survey undertaken by researchers at Harvard and Northeastern Universities has found that only 22% of Americans bought guns without undergoing a background check. The study, published in the Annals of Internal Medicine, updates the oft-cited claim that 40% of Americans purchased guns without background checks.

The “40%” statistic, often cited by proponents of gun reform, comes from a 1994 survey, and has been called a “lie” by the NRA.  “It’s crazy that nobody has asked these questions since 1994,” said Deborah Azrael, researcher at the Harvard School of Public Health. “I mean, should we be citing 20-year-old statistics in support of contemporary policy? Probably not, but the problem is that there has been no effort to maintain any kind of ongoing check on what has been happening.”

Researchers asked 1,163 gun owners if they had undergone a background check for their most recent firearm purchase, and whether or not the seller asked to see a firearm license or permit before making the sale. Only 22% of the respondents who had bought a gun in the past two years did so without a background check. In contrast, 57% of respondents who acquired their weapon over five years ago reported that they bought the gun without a background check.

The survey also exposed ways that people avoid background checks when purchasing firearms. 77% of people who bought guns from friends or acquaintances did not undergo a background check, and 45% of those who bought guns online also did so without a check. The researchers also found that gun owners in states that require background checks on private gun sales were more likely to report passing a check than those in states without these laws.

The study represents the most thorough investigation of gun ownership and background checks in decades, but because the data comes from a self-reported online survey, it may not be entirely accurate. The respondents may have misremembered or lied while taking the survey, and no attempt was made to verify their claims.  Still, Azrael feels that the study shows that “we've been moving in the right direction.”