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NYC Crime Rates

Is crime down in New York?  Turns out the answer depends on which crimes you count and possibly how you count them.  Tamer El-Ghobashy reports in this year-end article in the WSJ, "Based on the latest NYPD statistics, overall crime was down 1.4% through [Dec. 26] compared with the same period in 2009. However, murder, rape, robbery and felony assault remain higher than last year."

Crime indices typically count numbers of crimes without weighting for severity.  Because crimes tend to occur in inverse proportion to severity, crime indices tend to reflect the rates of the least serious crimes included in them.  The FBI's violent crime index is mostly an index of robbery and aggravated assault, with murder and rape rates having little effect.  The overall crime index is dominated by property crimes, which are more numerous than violent crimes.

According to the article, academics Eli Silverman of John Jay College and John Eterno of Malloy College think NYPD is cooking the books by downgrading some of the property offenses to charges that sink below the radar of the index.  However,  "A Wall Street Journal analysis of those numbers, assisted by professors on both sides of the statistics debate, found there were no obvious trends to indicate that index crimes were being downgraded into misdemeanors."

A skew between violent and property crime rates is consistent with what one would expect from the policy trends in New York, emphasizing improved policing and deemphasizing punishment.

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