Re: [UC] Not to "scare" you, but forewarned is forearmed

[Anthony West]

Liz wrote: > But, the last time I checked FBI statistics > Muggings were more common in Society Hill > Car Break ins more common in Rittenhouse Square > and Rape more common in both SH & RS than in UC. For you data nuts out there, the interpretation of crime stats -- like any other stats -- is fraught with subtle methodological challenges. The more you look into them, the less they tell you. One important point to keep in mind is that "crime rates" are based on this fraction: crimes reported divided by *residential population* of an area. But *crimes* aren't based on the residential population of an area. Criminals commit crimes against *targets*. And there is no easy way to measure the targets in a given area. Individual people can be targets of crime. But people move around from one area to another all the time. You can go to work in Conshohocken, shop at Plymouth Mtg. mall after work, go out for dinner and a movie in Manayunk, and come home to University City. So if your car is broken into at the mall, your *crime* will be factored into the Plymouth Mtg. crime rate -- but *you* won't be factored into the Plymouth Mtg. crime rate! What then is it measuring, really? Some obvious statistical biases appear in crime rates as a result. "Bedroom suburbs" will have lower rates of crimes against persons, because half the person who live there aren't physically present for 40% of the day. Destination neighborhoods -- where large numbers of people pour into for work or shopping or recreation -- will have correspondingly elevated crime rates. Center City has, say, 200,000 people who are in it at any given hour from 7 a.m. to 7 p.m., and they should attract 200,000 people's worth of assaults and purse-snatchings. But these crimes are *counted against* the 60,000 people who own beds in Center City. The result is a crime rate that soars above other neighborhoods; but that doesn't mean the actual *risk to an individual* is higher in Center City than it is in Mount Airy. You can see this phenomenon in statewide crime statistics. States like Florida and Nevada have high rates of crimes against property; states like Kentucky and Iowa have low rates. But that's because huge numbers of tourists pour into Florida and Nevada, for criminals to target their cash. By contrast, people who want to rip off Iowans and Kentuckians will usually find them somewhere else at least 2 weeks a year, visiting places like Las Vegas and Orlando. There are more alcohol-relared crimes per capita in South Jersey than in Southeastern Pennsylvania. But that's partly because many Pennsylvanians drink in New Jersey all summer, while few New Jerseyans drink in Pennsylvania all winter. University City is a destination neighborhood. It receives a huge daily net influx of commuters and transients passing through it who live elsewhere. Its crime rate cannot be compared meaningfully against the crime rate of an end-of-the-line suburb, or a neighborhood like Fox Chase. -- Tony West