And statistically you probably never will.
Based on violent crime rates over the past 20 years and changes in gun law, I can say with reasonable certainty that concealed weapon permits do not alter violent crime rates. They cause very little if any change.
Liberal propoganda at it's finest.
How so? There doesn't seem to be any strong correlation between violent crimes and concealed weapon laws.
I shall provide better evidence in about 18-20 hours.
The problem is those findings go both ways, if there is no corelation between gun laws and violent crimes, then what exactly is the reason for strict gun laws if they do not curb violent crime?
Something has curbed violence. But having a concealed pistol permit isn't what has. It is my belief that improved crime prevention has helped. Followed by the restrictions on assault weapons and automatic weapons as well as stricter control on who can get a gun.
The problem isn't that people who can responsibly use guns carry them, it's people who shouldn't have guns that get them somehow either legally or illegally.
Strict gun laws help by keeping those who shouldn't have a gun from easily obtaining one. It's not foolproof and is often circumvented by the black market, but with strict gun laws, those who sell such guns have to find more creative ways to keep their inventory hidden.
There doesn't seem to be any strong correlation between violent crimes and concealed weapon laws.
That's why people carry concealed. If you want to show evidence of something of a counter point, show where carrying causes more harm than it does good.
Why would I want to show something false?
See, Liberals and Republicans can get along 
I had a very long conversation with someone about 7 years ago on this subject. His argument and my subsequent research made me conclude that most people who carry guns legally are fine and those people don't have "crimes of passion" often enough to change the statistics. I also found that they don't actually help very often either so I figure, why bother fighting it? Let them have their guns. I personally prefer swords but that's just me.