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Box Cutter Stats

November 29, 2016

Yesterday I heard a segment on WNYC on the effort to decriminalize box cutters in New York State. I guess it’s up to Governor Cuomo to sign it into law.

During the segment we hear a Latino man who tells his story: he was found by cops to be in possession of a box cutter and spent 10 days in Rikers. He works in construction and having a box cutter is literally a requirement for his job. His point was that the law made it too easy for people with box cutters to end up unfairly in jail.

It made me wonder, who actually gets arrested for possession of box cutters? I’d really like to know. I’m guessing it’s not a random selection of “people with box cutters.” Indeed I’m pretty sure this is almost never a primary reason to arrest a white person at all, man or woman. It likely only happens to people after being stopped and frisked for no particular good reason, and that’s much more likely to happen to minority men. I could be wrong but I’d like to see those stats.

It’s part of a larger statistical question that I think we should tackle: what is the racial discrepancy in arrest rates for other crimes, versus the population that actually commits those other crimes? I know for pot possession it’s extremely biased against blacks:marijuana_use_rate_by_race_yearmarijuana_arrest_rates_by_race_year

On the other end of the spectrum, I’d guess murder arrests are pretty equally distributed by race relative to the murdering population. But there’s all kinds of crimes in between, and I’d like some idea of how racially biased the arrests all are. In the case of box cutters, I’m guessing the bias is even stronger than for pot possession.

If w had this data, a statistician could mock up a way to “account for” racial biases in police practices for a given crime record, like we do in polling or any other kind of statistical analysis.

Not that it’s easy to collect; this is honestly some of the most difficult “ground truth” data you can imagine, almost as hard as money in politics. Still, it’s interesting to think about.

Categories: Uncategorized
  1. November 29, 2016 at 7:46 am

    Two things:

    1. One thing I liked about the discussion of predictive policing in WMD was the assertion that our idea of justice demands that we be judged by our actions alone, not of “people like us”, no matter how defined. So even if a statistician could even out the burden in designing police practices, would we still not be being judged by the actions of “people like us”, just in a more sophisticated manner?

    2. The “related links” leads to Frank Pasquale’s “Black Box Society”, presumably because of the words “box” and “black” in the article. But a “black-box cutter” would be an excellent invention.


    • November 29, 2016 at 8:14 am


      My main goal, if I had this data, would be to force people to think harder about what ground truth looks like in criminal justice. For many people, including many data scientists, they take arrest records as their ground truth. The idea would be to quantify how misguided that assumption is.

      Agreed about the snazzy new term.



      • November 29, 2016 at 9:57 am

        Cathy: a valuable goal and I’m sure it’s one that does need case-after-case-after-case demonstration to achieve. The pot charts deserve wide circulation too.


  2. MikeM
    November 29, 2016 at 10:28 am

    Cathy, you should know better than this. Last month I was asked to review a paper for PPNAS that showed that used Simpson’s paradox to show that, yes, blacks are proportionally killed by police more often than whites. Part of my review:

    “The racial composition of a geographic unit is only one variable that can be used as a denominator; there are others. Consider the fact that, in most cities, the areas with the greatest crime rates are populated with minorities. In Chicago, the city I know best, there are two high-crime areas: the rest of the city is relatively safe. These two areas are characterized by a high rate of calls for police service, high crime and non-police shooting and killing rates, high poverty, high truancy rates, etc. These areas have the highest ratio of police per citizen and are more dangerous for police as well as for the 95% of the citizens in those areas that do not commit crime. In other words, using just race as a denominator truly obscures the picture. What if you did a neighborhood-level study with different denominators: number of violent crimes, number of shootings, or number of confiscated weapons? If you are trying to model the behavior of police, you should focus on what may drive their behavior!” [And, I should add, what may drive their deployment strategies.]

    So, is it not possible that, in cities where MJ possession is a crime, the police are proactively on the street looking to prevent mayhem, and in so doing find that they are doing so more often in Black communities?


    • November 29, 2016 at 10:32 am

      Not only is that possible, I think that’s exactly what happens. But that’s not to say it’s just!

      Liked by 1 person

      • MikeM
        November 29, 2016 at 10:41 am

        Not entirely just, perhaps, but that’s only one criterion that should be used in judging the worth (and outcome) of a strategy. What about the safety of community residents, their ability to walk safely through their neighborhoods, let their children play outside?

        It is also true that some execrable deeds have been done by police officers, in Chicago and elsewhere. But there has to be a balance between condemning all police actions and maintaining safety and security in neighborhoods truly riven by crime.


      • MikeM
        November 29, 2016 at 10:52 am

        I guess it’s equivalent to Type 1 and 2 errors: false alarm (too much proactive policing) vs missed detections (crimes). Balancing the two is not easy.


    • Josh
      November 30, 2016 at 9:19 am

      Mike M. That is probably part of what is going on and arguably reasonable, unbiased, actions by police. But there are also many areas where police have discretion and evidence suggests they make different judgments based on race — and surely other contextual factors. So, a white person, even in an unsafe neighborhood, may get off with a warning if found with a box cutter while a Black person is more likely to be arrested.


      • MikeM
        November 30, 2016 at 9:36 am

        I’m not sure I agree with you. In police work for the most part, geography is destiny. A white person with a box-cutter (or MJ) in an unsafe (i.e., minority) neighborhood might be looked upon more, not less, suspiciously. But I think that we’re looking at individual cases, as do Lloyd and Aaron in this thread; I’m talking about police policies.


  3. November 29, 2016 at 10:49 am

    What if the foundation for this obvious discrimination is focused on people that live in poverty or look like they live in poverty?

    The reason I ask this is because of my older brother (he died in1999 age 64). When he was a teen he dressed like a street gangster with his pants hung low on his hips. He walked like a gangster. He had body art on his skin. On one arm he had a snake coiled from his wrist to his shoulder. On the other was a nude woman, and when he flexed his muscles, her breasts exploded in size. He had an attitude. His language was gutter/gang. He also smoked pot and drank too much. He spent 15 years of his life in-and-out of prison. or as he referred to it, the slammer.

    When I was a teen, I didn’t run with street gangs, had no body art, and never dressed like my brother even though he tried to influence me to be like him. I went into the Marines right out of high school. When I returned home from Vietnam and was on leave, I was pulled over by the police for driving while very drunk. My hair was cut jar head Marine Corps style, and I was obviously dressed in reasonably priced, clean-cut, middle class clothing. The police put me in the passenger seat and had the pregnant girl, not drunk, with me drive even though she had no driver’s license, but the police didn’t ask her if she did. The police did not write me up or arrest me. The car I was driving was one I bought on my return from Vietnam with the money I’d saved from combat pay (in combat the troops are paid more than they get paid outside of a combat zone), and that car was a Buick and had prosperous middle class written all over it.

    Every time my brother was stopped for drunk driving, he went to jail. We were both born into a family that lived in poverty with parents who were high school dropouts, and more people of color, blacks and Latinos/Hispanics, live in poverty than whites.


    • Aaron Lercher
      November 29, 2016 at 11:22 am

      Here’s a “driving-while-middle-class-and-white” story, much more boring than yours.

      Rural Louisiana, driving an old car with an Obama bumper sticker and one headlight out. Oh oh. It was twilight and I was on my way back to Baton Rouge after hiking in the woods. A police officer stopped me but let me go without ticketing me or worse. He was very nice. That’s the whole story.

      This kind of incident might be overlooked in crime statistics. Maybe police need to count “non-arrests.”


      • MikeM
        November 29, 2016 at 1:19 pm

        That’s on its way, finally: the newer thinking in policing is that “crimes averted, not arrests made, should be the primary metric for judging police effectiveness. “


  4. ~
    December 1, 2016 at 8:36 am

    “On the other end of the spectrum, I’d guess murderers are pretty equally distributed by race relative to the murdering population. ” Why don’t you investigate this particular hypothesis, and tell us what you find.


  5. Daniel
    December 1, 2016 at 4:30 pm

    You say that you suspect murder arrests to be fairly equally distributed by race relative to the murdering population. My impression, mostly from reading Jill Leovy’s book and watching The Wire, was exactly the opposite: in high crime black neighborhoods in places like Chicago and LA, police simply don’t have the resources to crack all the homicide cases, and are not necessarily even aware of all murders being committed. I’d definitely be interested to see more number on this point.


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