To illustrate a social trend that amounted to a spectacular crime drop in the Big Apple throughout the 1990s and 2000s—as described by Franklin E. Zimring in the August 2011 issue of Scientific American, we mapped two decades of New York Police Department crime statistics precinct by precinct.
In the first map below, we combined data on the six most serious crime categories into one index. The other maps (click to unroll) illustrate the incidence of each type of crime.
(Find details about individual New York City precincts here.)
How the weighted crime index was derived
In the first series of panels relating to total crime, the color of each precinct represents a combined crime index. This index is the weighted total of the six crime types under study (homicide, rape, assault, robbery, burglary and car theft) reported in that precinct.
"Weighted" means that we didn't simply add up the raw numbers. Instead, for each crime type all numbers were rescaled (multiplied by a common factor) first. In the case of the 1990 statistics, the rescaling was the same as expressing the numbers as percentages of the citywide totals for that crime.
Thus, if in 1990 precinct X had 4 percent of all homicides, 4 percent of all rapes, and so on for each of the other four types of crime, the combined crime index for that precinct would be:
4 + 4 + 4 + 4 + 4 + 4 = 24
(Note that the combined crime index of all precincts totals 600, because the percentage for each crime type adds up to 100 percent citywide, and we are combining six categories.)
For subsequent years the number of crimes of each type in a precinct was divided by the 1990 citywide total for that crime instead of that year's citywide total.
Consequently, if in 2000 precinct X still reported exactly 4 percent of each type of crime committed in the city, but the actual numbers in that precinct had all dropped by half, its combined crime index for 2000 would be 50 percent lower than in 1990:
2 + 2 + 2 + 2 + 2 + 2 = 12
We used this combined crime index rather than simply adding raw numbers for all types of crimes because it provides a clearer comparison of how the numbers in each district stack up relative to the 1990 baseline. Simple addition of the incidence of each crime in a district could have hidden profound variations from precinct to precinct or from year to year, because numbers are vastly different for different crime types (thousands in the case of homicides, for instance, tens of thousands in the case of burglaries). If a precinct went from 10 homicides and 90 car thefts in 1990, say, to zero homicides and 100 car thefts in 2000, the simple addition would yield the same result for both years—but most people would consider the area to have become much safer.
— Davide Catelvecchi
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Maps by XNR Productions; SOURCE: NYPD (raw data by precinct)
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8 Comments
Add CommentDoes this have anything to do with aging baby-boomers? In other words were the criminals a result of post-World War Two overcrowding of schools and social unrest then they either were jailed, killed off or got married and settled down?
Reply | Report Abuse | Link to thisThe article does not mention if the figures are adjusted for population changes. It's possible that there are simply fewer people, although it is possible that the is just a result of population aging as AtlantaTerry suggests. Without knowing the other factors, it's hard to draw a conclusion.
Reply | Report Abuse | Link to thisfacts are that crime is down, generaly speaking, everywhere it is measured. it is interesting that the first reaction of most people to this factual imformation is disbelief or an attempt to explein the fact away, while holding fast to their previous belief that crime is worse today than it was in the past.
Reply | Report Abuse | Link to thiswe live in a world with less crime, less violence, less hunger, less war, less terrorism, less famine, less disease, less injustice, less privation than has evert existed. we choose not to believe this. our beliefs, are meintained, even when they are in direct contradiction to facts.
Zimring's article in this month's issue does mention that the demographics of New York City has not changed much overall -- in other words, it says that there are not fewer people and that they are not older.
Reply | Report Abuse | Link to thisPeople get really annoyed when I point out that things just keep getting better. Particularly right wing Christians that want armageddon which requires tribulations that simply are not happening any more than they ever did. Individual natural disasters have impact on more people primarily because there are more people. There has been a slight uptick in natural disasters recently but well within statistical probability.
Reply | Report Abuse | Link to thiscognitive neuroscience explains why. subconscious processes are tuned to detect and respond to potential threats; we are presented with 'news' and entertainment sources that disproportionaly tells us about crime, war, violence, human evil and tragedy, providing a large number of easilly accessible memories of bad things happening; we are never, or rarely presented with meaningful information or statistics that allow us to put crime, was, famine, etc in proportion or perspective, and when we are we are daunted because subconsciously and consciously, we are bad at math and understanding what number above 7 really mean; we are risk averse; etc, etc, etc. the fault is on ourselves, our lack of self awareness and our poor education, which fails to provide the majority of students with the ability to think criticaly.
Reply | Report Abuse | Link to thisA very informative article, but as a resident of New York City during the 70's through the mid 90's I remembered other items that may have contributed to the crime drop. First after Giuliani was elected he changed the NYPD uniform. It was a sky blue that was adapted in the early 70's from what I heard to appear friendlier to the public. The new uniform was a dark navy blue and it was done to make the police look more like an authority figure. Secondly including Giuliani election in 93, in 94 Pataki was elected governor. This was the first time in many years where Republicans were leading the city and the state. And third the death penalty was re-established shortly after Pataki took office, it would always pass the assembly but the governor would always veto it during the late 70's and 80's. Again, not sure if these three items had any effect on the overall crime drop but it I think that they should be discussed.
Reply | Report Abuse | Link to thisThis issue of falling crime is extensively discussed in the book "Freakonomics". It correlates very well with Roe V Wade. The unwanted children stopped being born and stopped being neglected and turning into criminals.
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