you are the sort of person who likes guessing games, you may wish to spend the next few moments pondering which of the preced- ing explanations seem to have merit and which dont. Hint: of the seven major explanations on the list, only three can be shown to have contributed to the drop in crime. The others are, for the most part, figments of someones imagination, self-interest, or wishful thinking. Further hint: one of the greatest measurable causes of the crime drop does not appear on the list at all, for it didnt receive a single news- paper mention.       Lets begin with a fairly uncontroversial one: the strong economy. The decline in crime that began in the early 1990s was accompanied by a blistering national economy and a significant drop in unemployment. It might seem to follow that the economy was a hammer that helped beat down crime. But a closer look at the data destroys this theory. It is true that a stronger job market may make certain crimes relatively less attractive. But that is only the case for crimes with a direct finan- cial motivation-burglary, robbery, and auto theft-as opposed to vi- olent crimes like homicide, assault, and rape. Moreover, studies have shown that an unemployment decline of 1 percentage point accounts for a 1 percent drop in nonviolent crime. During the 1990s, the un- employment rate fell by 2 percentage points; nonviolent crime,   meanwhile, fell by roughly 40 percent. But an even bigger flaw in the strong-economy theory concerns violent crime. Homicide fell at a greater rate during the 1990s than any other sort of crime, and a num- ber of reliable studies have shown virtually no link between the econ- omy and violent crime. This weak link is made even weaker by glancing back to a recent decade, the 1960s, when the economy went