I'm swimming a bit out of my lane, but I'd say two things, based on general knowledge.
Statistics Canada can do special data projects in which they mine the data they receive from the provinces and territories, from the police forces and from the court systems. That's a qualitative data analysis that they would be able to do.
Another way to do it—and I know, because you've been talking about it a lot—would be looking at whether new criminal offences could be added to the code, for example, which then provides, specific to ghost guns, a better data point to measure against. If there is a specific offence, then there's a charge entered with respect to that offence, and Statistics Canada is able to pull that information.
Those would be the two ways I can think of.