Much of the national debate on gun reform is focused on access to assault rifles — a common choice of weapon for perpetrators of violent mass shootings.
In order to propose legislation, lawmakers often rely on the work of policy researchers to determine how effective these reforms would be.
But researchers say data on legal gun ownership is not as easy to come by as the weapons themselves.
Ken Wilbur, a professor of marketing and analytics at the Rady School of Management at UC San Diego has studied the issue. He says that because data on gun ownership is scarce, he has had to use proxies.
"There are a handful of state governments — including Massachusetts and California — that require licensed firearm retailers to enter new sales into a state database, but that's very much the exception than the norm," he said. "And, those states don't publish their data for researchers to analyze."
Wilbur joined Midday Edition on Wednesday with more on the challenges researchers face in gathering gun ownership data.