As some 70,000 people attended the NRA’s annual convention last week, nearly three months after the horrific school shooting in Parkland, Fla., the reignited national debate on guns seems to be at a stalemate.

But the discussion lacks some basic facts about guns in the United States. For example, how many people in the United States own a firearm? As with most gun issues, the answer is hotly disputed. Perhaps just as important, what do Americans believe to be the percentage of their fellow citizens who own guns — and will that increase or decrease in the coming years?

Our research finds that Americans substantially overestimate the gun-owner population — and that what they believe about gun ownership is related to what gun policies they support.

People overestimate the size of the gun-owner population

From June 28 to July 1, 2017, we commissioned Survey Sampling International to conduct a representative survey of 2,089 American adults. Survey respondents were asked, “Out of every 100 people in the U.S., about how many do you think own a gun?”

Typically, when confronted with such a question, people overestimate the size of minority populations. Researchers call this political innumeracy, or lack of knowledge of politically relevant numbers. Several studies reveal substantial innumeracy in estimating the size of African American, Hispanic, immigrant and gay and lesbian populations.

And that’s what happened in this case. Drawing on sources cited by gun rights and gun regulation groups, we estimated — generously — that roughly 20 to 30 percent of Americans personally own one or more guns. Our survey respondents, however, estimated on average that 43 percent of their fellow citizens own guns — a significant overestimate. What’s more, nearly 45 percent of our respondents estimated that 50 percent or more of the U.S. population owns at least one gun.

Frustration is boiling over on both ends of the political spectrum at the inability to stop mass shootings, but many still can't agree on a path forward. (Jenny Starrs/The Washington Post)

Americans foresee a gun-owner majority

Next, we asked, “Now thinking about 10 years in the future, 2027, out of every 100 people in the United States, about how many do you think will be gun owners?” The average response was 56 percent.

In other words, most people in our survey expect that gun owners will be a majority of the U.S. within 10 years.

For each respondent, we compared that forecast with their estimate of the current population of gun owners, to see how they thought things would change. Sixteen percent thought gun owners would become a smaller percentage of the population; 12 percent thought there would be no change; and a whopping 72 percent thought gun ownership would expand. That’s extraordinary, considering that 30 years of data show either a decline or rough stability in personal gun ownership.

Gun owners report higher estimates than non-gun owners

In estimates like these, research suggests that people’s personal experiences influence their perceptions about the size of minority populations. For example, both white and black Americans who said they often had interactions with African Americans overestimated the African American population. Similarly, people who reported knowing a gay person estimated a larger gay population than those who did not. Similarly, neighbors of immigrants were more likely to offer higher estimates of immigrant populations than those living in neighborhoods without immigrants.

Given all this, we suspected gun owners would likely overestimate the gun-owner population. After all, gun owners often attend gun shows, read trade magazines, receive targeted advertising from gun interests, possess NRA memberships and practice at firing ranges. They often come into contact with other gun owners — certainly, more often than do non-gun owners.

And, indeed, that was the case. On average, gun owners estimated that 45.5 percent of Americans own guns — while non-gun owners estimated that figure at 39 percent. Gun owners also foresee a considerable increase in gun ownership, estimating the impending population at nearly 60 percent, more than the 53 percent forecast from non-gun owners. Notably, both groups believe that by 2027, a majority of the population will own guns.

Do estimates of gun ownership matter?

Finally, we discovered that perceptions of the size of the gun-owner population are associated with people’s views on gun policy.

We asked respondents, “How strongly would you favor or oppose new laws that would restrict access to gun ownership?” After controlling for other variables that influence opinions about gun policies — in particular, party identification, ideology and gun ownership — we found that those who offered higher estimates of the U.S. gun-owner population tended to oppose laws restricting gun ownership.

What do we make of this innumeracy?

Americans believe that the United States has an extravagantly large gun-owner population. More than 40 percent of the public estimated that a majority of Americans own guns. About 18 percent think that 70 percent or more of Americans own guns.

In reality, only about 25 percent of Americans own a gun.

In addition, more than 70 percent of our respondents believe more people will own guns in the near future — while the actual data suggest that the percentage will either decline or hold steady.

Of course, gun-rights advocates and opponents may continue to fight over these numbers. Research suggests that people who believe misinformation often resist correction.

In the “post-truth” era, these exaggerated perceptions of gun ownership may make it easier for legislators to pass laws expanding gun rights. After all, if most constituents own a gun — and more will do so in the future — then supporting gun rights makes political sense. And these overestimates might even influence Americans’ beliefs about whether they themselves should buy a gun. After all, if you think most people own one, shouldn’t you be prepared as well?

Mark Joslyn is professor and graduate director of political science at the University of Kansas.

Don Haider-Markel (@dhmarkel) is professor and chair of political science at the University of Kansas.