yea we never know but I think it's safe to say it will reduce (but not drastically) crime rates. Think about it - federal minimum wage is $5.85 per hour. What the heck can you do with it????? You can't even pay for apartment rent, basic amenities, and food sufficiently! Boosting it up to, let's say, $7-8/hr will take a handful of load off from working parents by working less hours and more hours on children. Maybe they can even afford some stuff for kids like books and clothes for schools. Increased parental involvement in child's life is a great deterrent to becoming a criminal.
Poverty life means you live in broken homes infected with drug addicts and rats - an embarrassment to themselves. They want to feel like they contribute to something. Working at McDonald as grill guy for $5.85/hr for 8+ hours is not exactly cool. You're a nobody.
Kids join gangs because they want to be "somebody" - an identity. Yes being in gang or being a thief means you can make quick bucks in short time. But more importantly - "gang" is such a complicated social issue. I suppose I can say it's like joining military to explore the world and see some actions - joining gangs - you get to get laid, have access to drugs and guns, and see some actions (killing).
We all want stuff - flat-screen tv, cables, cars, clothes, toys for kids, etc. Working $5.85/hr full-time is not really get you any one of those. You can't really afford to pay for one gas refill either. Increasing minimum wage will help some even if it means preventing 2 kids out of 200 from joining gangs today. Every bit counts!