Police Data

One afternoon on a remote work day, you are sitting at home, looking out the window before getting back to work on that TPS report that's due Monday. Outside, you see someone walking slowly down the street -- someone you don't recognize. "Who is that guy? What's he doing here?" you think to yourself. And maybe, "He seems suspicious. I think I'm going to call the police." It's important that we all work together to keep our communities safe. But sometimes, our natural tendencies can end up making our communities hostile and unsafe for innocent people.  "Bias by proxy" is an effect that can happen if the police get called for "suspicious people," and those calls are biased by race. If a Black man walking down the street is perceived as suspicious, and someone calls the cops to check up on him, then innocent Black people are going to get stopped and questioned by the police. Even if the police aren't biased, there will be bia...

 It was the summer of George Floyd that really shook my confidence in the police. Like most white kids, I was raised on the image of the friendly policeman -- if you ever have trouble, find a policeman (they were always men back then) and he will help you. But as more and more stories emerged... as more and more departments were revealed to have covered up, condoned, and even rewarded the most grotesque racism... and as I really listened to people of color talking about their own experiences, my childhood image was shaken. I respect all of those lived experiences. They are real and true. At the same time, the thing that I can offer to help is data analysis. That's not a very splashy gift; sorry about that. But it's what I have, so it's what I bring. One thing about data analysis is that you really can't do it in a vacuum, without context. It's not a machine, where you pour numbers in at the top and get crisp and unambiguous answers out the bottom. You have to know t...

 An article came out in this week's Town Crier headlined "Peace of Mind comes at a price as residents pay for private security. " It is a subtle headline, but a good one -- it points out right at the top that "peace of mind" is all the residents of Los Altos Hills are getting. Essentially, the article is telling the story of how a group of about 85 residents each ponied up $990 (on average) to hire a private security firm to drive around town. It is undeniable that the private security gave those people "peace of mind." They certainly felt safer. But were they safer?  Of course, the authorities pull out the usual combination of "crime just keeps rising" and "obviously this will help." If there is anything this blog is about, it's to ask "Really?" every time we hear those phrases. So let's look at the claims in the article, and see what the data says. Claim #1:  There were 48 burglaries in Los Altos Hills between Ja...

Rebecca Crosby, Judd Legum, and Tesnim Zekeria have a great article out on Popular Info. They use available police data to evaluate the claim that Target made as to the reason for its store closings. Most media was happy to just believe Target spokespeople when they explained why they were closing 9 Targets across the country: they were just losing too much money from theft in those stores to be viable. Crosby, Legum, and Zekeria found a clever way to test that hypothesis. In New York, San Francisco, and Seattle, they were able to find crime data for the immediate area near the Targets that were closing, and also around nearby Targets that were staying open. If the closing Targets were chosen based on high crime, they reasoned, we should see it in the police data. In fact, they found that crime in the immediate area around nearby stores was equivalent to or greater than the crime nearby the closing stores. This seems to pretty effectively rule out the hypothesis that the stores were c...