The study was funded by the London-based Centre for Crime and Justice studies.
Oliver, a sociologist who studies crime at the University of Wisconsin, Madison, says it isn't clear how to combine data from prison surveys and from national surveys that exclude prisoners.
Last year, a report by the independent Centre for Crime and Justice Studies said spending on overtime in England and Wales had increased by 90% since 1998 despite a record rise in the number of officers.
Mark Kleiman, a professor who studies crime policy at the University of California, Los Angeles, said that by enforcing laws, authorities in New York are keeping people off the streets who are more likely to be committing serious crime.
The magazine, which is the journal of the Centre for Crime and Justice Studies at King's College London, said there were a further 14, 600 held under the Mental Health Act, 2, 300 in immigrant detention centres and about 470 in child prisons and secure children's homes.
Charles Goredama, an expert on organised crime at the Institute for Security Studies, thinks there are fewer, between 75 and 100 gangs, with perhaps 10, 000 active members prepared to be violent.
Studies show that street crime such as shooting deaths cost communities more than lives, Pollack said, citing emergency medical services and criminal investigation as tangible costs along with intangibles such as residents moving away to escape the threat.
Just look at the 1920s, says David Kennedy, director of the Center for Crime Prevention at John Jay College of Criminal Studies.
Studies show that half of violent juvenile crime occurs between 2 p.m. and 8 p.m.
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"The government should be getting its own house in order first, " agrees Frank Cilluffo, deputy director of the Global Organized Crime Project at the Center for Strategic and International Studies.
In a 1999 poll conducted by the Joint Centre for Political and Economic Studies, blacks were twice as likely as whites to cite crime, violence and drugs as the most important problems facing the country.
Immigration also matters, he says: studies have repeatedly shown that cities with large immigrant populations experience lower rates of violent crime.
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Studies continue to indicate that one of the contributing causes of poverty, illegitimacy, crime, inadequate education and other socioeconomic problems is the absence of married, committed parents in a family.
He also spotlighted studies showing children who attend preschool have lower teen pregnancy rates and are less prone to engage in violent crime.
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