After 17 people died during the Parkland school shooting in Florida two weeks ago, many lawmakers and gun control advocates have called for tighter regulations on who can buy and keep guns.

The National Rifle Association has rebuffed those calls. But a new study published Wednesday in the New England Journal of Medicine is suggesting that firearm injuries actually drop during the group’s annual conventions — when roughly 80,000 members, and their guns, are off the street and in meetings.

The study addresses the question: “What is the risk of a gun injury just simply by using guns alone?”

The study analyzed nearly 76 million private insurance claims filed nationwide for people under age 65 — specifically, from emergency department visits during convention dates between 2007 and 2015, plus three weeks before and three weeks after each annual meeting.

When conventions weren’t happening during that roughly six-week window, firearm injuries occurred at a rate of 1.5 per 100,000 people, the report says. But during conventions, that rate dipped to 1.2 per 100,000 people — a 20-percent drop nationwide, according to the study.

Anupam Jena, the lead author on the study, is an economist and physician with an eye for Freakonomics-style research. He has studied how marathon routes clog city streets and hurt survival rates for heart attack patients. He has explored the relationship between major cardiology conferences and health outcomes for heart disease patients.

In his latest study, Jena, an associate professor of health care policy at Harvard Medical School, wanted to know what data revealed about firearms injuries nationwide when tens of thousands of gun owners suddenly leave home and head to the same location.

What drove Jena to conduct this analysis was the argument that if people were trained to use guns more safely, then fewer gun injuries would occur. In the report, the authors suggest “firearm-safety concerns and risks of injury are relevant even among experienced gun owners.”

The NRA did not immediately respond to a request for comment on the study.

This observational study does not provide conclusive evidence about the NRA’s influence on gun safety overall and “cannot be causally attributed to the meetings themselves,” the report said. But Jena said the study does raise an important question: “What is the risk of a gun injury just simply by using guns alone?”

It’s a question that has dominated political debates in the days since a gunman entered Marjory Stoneman Douglas High School and opened fire on students and teachers, killing 17 people.

There’s not much federal research on gun violence. In 1996, Congress passed a provision known as the Dickey Amendment, that said the Centers for Disease Control and Prevention can’t use funding to “advocate or promote gun control.” That does not directly rule out research, but has had what many have called “a chilling effect” on what data the agency has produced. Some lawmakers have called for rolling back that provision.

This latest study, while statistically significant, is “not necessarily meaningful,” said Mark Rosenberg, the president emeritus of the Task Force for Global Health and the founding director of the National Center for Injury Prevention and Control. It highlights the fact the the United States has “so little meaningful data.”

The United States has “so little meaningful data” on gun violence that “we’re so ill-prepared to answer the most compelling questions.”

“We’re so ill-prepared to answer the most compelling questions” about gun violence, said Mark Rosenberg, the president emeritus of the Task Force for Global Health and the founding director of the National Center for Injury Prevention and Control. “If you don’t know what works, you can claim anything works.”

Rosenberg said the country needs to appropriate money so the CDC can collect “large-scale, multi-jurisdictional data” about gun violence to better understand what the problem is, what causes are driving it, what solutions work and how to scale them up.”

Republican Govs. Rick Scott of Florida and Bill Haslam of Tennessee , split from the NRA and their party on tightening gun control laws after Parkland. Both said they want to ban bump stocks, and Scott, who has been Florida’s governor during three mass shootings since 2016, said he wanted require that a person must be at least 21 before buying a gun.

During the Conservative Political Action Conference (CPAC) near Washington, D.C., NRA Executive Vice-President Wayne LaPierre criticized Democrats and the media as being elitists eager to attack the NRA and “eradicate all individual freedom.”

“No politician anywhere can tell the NRA not to come to their city … We are already there.”

“As usual, the opportunists wasted not one second to exploit tragedy for political gain” with calls for more gun control, LaPierre said, adding that the “breathless national media” was “eager to smear the NRA.”

On Feb. 19, Dallas Mayor Pro-Tem Dwaine Caraway stood before a bank of microphones and said the NRA should “reconsider coming to Dallas” this May for its annual convention. A self-professed “believer in the Second Amendment” who owns five guns, Caraway said he didn’t want to host the group until it came to the table “to solve the problem.”

Responding to Caraway’s comments, Andrew Arulanandam, the NRA’s managing director of public affairs, said in a written statement to the PBS NewsHour: “Dallas, like every American city and community, is populated by NRA members.”

“No politician anywhere can tell the NRA not to come to their city,” he said. “We are already there.”

Going forward, Jena said he wanted to analyze state Medicaid data to see if similar trends emerged during NRA convention dates.