There Are 900,000 Property Lots in New York City. How Do You Find the Unsafe Ones?

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March 6 2013 3:31 PM

Big Data in the Big Apple

How New York’s first “director of analytics” revolutionized the city’s building inspections.

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The analytics occasionally showed that some time-honored ways of doing things were not the best, just as the scouts in Moneyball had to accept the shortcomings of their intuition. For example, the number of calls to the city’s “311” complaint hotline was considered to indicate which buildings were most in need of attention. More calls equaled more serious problems. But this turned out to be a misleading measure. A rat spotted on the posh Upper East Side might generate 30 calls within an hour, but it might take a battalion of rodents before residents in the Bronx felt moved to dial 311. Likewise, the majority of complaints about an illegal conversion might be about noise, not about hazardous conditions.

In June 2011 Flowers and his kids flipped the switch on their system. Every complaint that fell into the category of an illegal conversion was processed on a weekly basis. They gathered the ones that ranked in the top 5 percent for fire risk and passed them on to the inspectors for immediate follow-up. When the results came back, everyone was stunned.

Prior to the big-data analysis, inspectors followed up the complaints they deemed most dire, but only in 13 percent of cases did they find conditions severe enough to warrant a vacate order. Now they were issuing vacate orders on more than 70 percent of the buildings they inspected. By indicating which buildings most needed their attention, big data improved their efficiency fivefold. And their work became more satisfying: They were concentrating on the biggest problems. The inspectors’ newfound effectiveness had spillover benefits, too. Fires in illegal conversions are 15 times more likely than other fires to result in injury or death for firefighters, so the fire department loved it. Flowers and his kids looked like wizards with a crystal ball that let them see into the future and predict which places were most risky. They took massive quantities of data that had been lying around for years, largely unused after it was collected, and harnessed it in a novel way to extract real value. Using a big corpus of information allowed them to spot connections that weren’t detectable in smaller amounts—the essence of big data.


The experience of New York City’s analytical alchemists highlights many of the themes of our book. They used a gargantuan quantity of data, not just some; their list of buildings in the city represented nothing less than N=all. The data was messy, such as location information or ambulance records, but that didn’t deter them. In fact, the benefits of using more data outweighed the drawbacks of less pristine information. They were able to achieve their accomplishments because so many features of the city had been datafied (however inconsistently), allowing them to process the information.

The inklings of experts had to take a backseat to the data-driven approach. At the same time, Flowers and his kids continually tested their system with veteran inspectors, drawing on their experience to make the system perform better. Yet the most important reason for the program’s success was that it dispensed with a reliance on causation in favor of correlation.

“I am not interested in causation except as it speaks to action,” explains Flowers. “Causation is for other people, and frankly it is very dicey when you start talking about causation. I don’t think there is any cause whatsoever between the day that someone files a foreclosure proceeding against a property and whether or not that place has a historic risk for a structural fire. I think it would be obtuse to think so. And nobody would actually come out and say that. They’d think, no, it’s the underlying factors. But I don’t want to even get into that. I need a specific data point that I have access to, and tell me its significance. If it’s significant, then we’ll act on it. If not, then we won’t. You know, we have real problems to solve. I can’t dick around, frankly, thinking about other things like causation right now.”

Excerpted from Big Data: A Revolution That Will Transform How We Live, Work, and Think by Viktor Mayer-Schönberger, Kenneth Cukier. Copyright © 2013 by Viktor Mayer-Schönberger and Kenneth Cukier. Reprinted by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Viktor Mayer-Schönberger is a professor of Internet governance and regulation at the Oxford Internet Institute in the United Kingdom. He is a co-author of Big Data: A Revolution That Will Transform How We Live, Work, and Think (Houghton Mifflin Harcourt, 2013).

Kenneth Cukier is the data editor of the Economist. He is a co-author of Big Data: A Revolution That Will Transform How We Live, Work, and Think (Houghton Mifflin Harcourt, 2013).