copt found this one
http://news.stanford.edu/2017/06/21/violent-crime-increases-right-carry-states/
Examining decades of crime data, Stanford Law Professor John Donohue?s analysis shows that violent crime in RTC states was estimated to be 13 to 15 percent higher ? over a period of 10 years ? than it would have been had the state not adopted the law.
My issue with this study is that it compares real world "violent crime" rates per-state with a fictional state. Texas vs. fictional Texas for example.
"Violent Crime" includes much more than crimes involving firearms
Why not compare the right-to-carry states with the states that have restricted firearms? Could it be that that data would show something unfavorable to the narrative?
(edit:) upon re-reading the story, the study apparently uses three states, California (1996 pop: 32 million) Nebraska (1996 pop: 1.7 million) and Wisconsin (1996 pop: 5.2 million) to create the fictional Texas, and compare it to real Texas (1996 pop: 19.3 million)
So Fake Texas would have a population of 38.9 million, vs. Real Texas population of 19.3 million. Seems legit.
The specific dates used could affect the results massively. For example, aggregate "violent crime" in the US peaked in 1991, slowly dropped until 1996 where it then drastically fell until the year 2000 where it remained relatively constant.
Further complicating the issue, in 2013 there existed no states which were "no-issue", meaning you could get a concealed carry license in every state. The only states which would not be included in this study, in 2017, would be California, New York, and a handful of smaller states on the east coast. These states have been "May-Issue" since 1996.
This brings me to another problem, the fact that concealed carry is not actually banned in these states. It may be costly and/or difficult to apply for a license, but if this study concluded in 2017 the synthetic data for the aggregate of all states would be far lower than the real data. All that this study proves is that synthetic predictions for statistics already collected in the real world don't match the real world data (WOWZERS!!)
I'm tempted to actually buy the article so I can really pick it apart (yes its behind a paywall, another issue I have with it)