Crime

Another example is in the crime world.  People commit crimes because people respond to incentives, and it’s the most attractive offer available to them.  The decision to commit a crime is a result of cost/benefit analysis. For instance, consider mugging and gun control. People against privately owned handguns propose that in a fight between a criminal and a victim, the criminal would win because they have more reason to learn to use a gun. But say that 1 in 10 little old ladies carry a handgun, and 1 in 10 of those mugged happen to kill the mugger.  On average, the muggers get the money, but by weighing the benefits and costs they may realize that the amount of money a little old lady has isn't worth the 1 in 100 chance of dying. So the muggings decrease, not from lack of muggers, but lack of desire to mug.  Thus to stop someone from doing something you don’t want them to, you don’t have to make it impossible, just unprofitable, and vice versa, for something in the economy such as marketing.

http://www.youtube.com/watch?v=Lp28Jgn-8e8
http://www.aic.gov.au/publications/current%20series/tbp/41-60/tbp042.html

Friedman, David D. "Crime." : The Concise Encyclopedia of Economics. Liberty Fund, Inc., 2008. Web. 15 Dec. 2012.
"Motion to Pull." RSS. TV Tropes Foundation, 13 Dec. 2011. Web. 15 Dec. 2012.
"Old Lady Stops Robbery at Jewellers Northampton Feb 2011." YouTube. YouTube, 08 Feb. 2011. Web. 13 Dec. 2012.
Dossetor, Kym. "Cost-benefit Analysis and Its Application to Crime Prevention and Criminal Justice Research." Australian Institute of Criminology. Australian Institute of Criminology, 18 Mar. 2011. Web. 13 Dec. 2012.