The FBI report that violent crime dropped 3.5 percent in the first six months of 2008 compared with the same period in 2007, while property crime fell 2.5 percent comes with caveats, reports the Las Vegas Sun. Because the compilation includes only reported crimes, it could mean that victims were too scared to file police reports, or worried it would get them deported. Or they figured it wouldn't do them any good, so why waste time on filing a report about that stolen car stereo?
A second system, the National Crime Victimization Survey, is a census used by academics in tandem with the FBI’s Uniform Crime Reports to get a sharper focus on crime trends – for the survey, more than 135,000 Americans self-report their own victimizations. There are problems with this methodology too, but the idea is that combined, two studies are – like bad news – better than none at all. (The victimization survey found in 2007 that only 46% of violent crimes and 37% of property crimes were reported to authorities.)