In 1986, the year before Florida started the wave of state RTC laws it had a population of 11.6 million people and 1371 murders. Fast forward to 2015 its population increased to 20 million but its murder rate dropped to 1041. In absolute terms that’s a 24 percent drop. Per capita it translates into a 50 percent drop. So his contention is that more people would have been murdered. There’s absolutely no way to know that number.
However, as the article notes: "The team estimates that the adoption of RTC laws substantially elevates violent crime rates (excluding murder rates..."
"To find out, the team projected what would have happened in right-to-carry states had they not relaxed concealed-carry standards, accounting for differences in demographics, policing, and economic growth."
So if the team concluded that economic growth is what caused lower crime in a state with RTC, they would increase the crime rate based on that, and then compare it to actual crime rates. Or they could compare changes in police tactics, decide how much that contribute, and then take out THAT effect to see what was left.
IOW, total bullshit!