Police Data

 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...

I'm working on some analysis on the article that came out in the Town Crier about Los Altos Hills hiring private security , but in the course of doing that analysis, I came across this interesting situation. So it goes in data analysis. Anyway, this turns out to be interesting. Los Altos Hills doesn't have their own police department; for now, they are contracting for police services from the Santa Clara County Sheriff's Department. The SCC Sheriff's department has incident data on CityProtect , which anyone can download. The trouble is, the incident data only includes the "block-sized address", and not the city where the incident occurred.  It's easy enough to see the "200 Block CAROL DR", put that into Google Maps, and see where it is. Turns out it's San Jose. But with around 32,000 incidents in the first 9 months of 2023, we need an automated way to do that. In a future post I'll nerd out about how to do that, but for now, just know th...

Another LAPD, perhaps slightly more famous than ours, has the motto, “To Protect and To Serve.” It is a sentiment I think we can all get behind – we want safe communities, and we would like the police department to help us achieve that. We seem to end up in a lot of confusion and disagreement, though, when we look at how to actually make that happen. I once had a mentor who would always, always ask: “What is your goal?” He would push me to think hard about what I wanted, what the desired outcome was, before getting down into the weeds of the implementation. Without knowing what we are trying to accomplish, it’s unlikely that we can come up with a very good solution. Being clear about goals helps our discussion in another way: we choose goals based on our preferences, desires, visions, and hopes. We (ought to) choose implementations based on empirical data. That is, once we’ve decided what we want, the question of how to get that becomes one of facts, not of opinions. Too often we get i...

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...

Last week we saw that crime -- property crime in particular -- is actually pretty low in Los Altos. Sure, okay. But look around, right? Crime is up, up, up! It's so much worse than it was a few years ago, right? Is it, though? Let's address this in two parts: What are the crime trends in Los Altos and the Peninsula? Why do our perceptions deviate from reality? Again, let's start with California. A certain former president recently called for the summary execution of shoplifters as the only way to stop the California crime wave. Here's what the California Public Policy Institute found : So, property crime is down almost 7-fold since its peak in the early 80s! I guess the good old days were not as good as we remember. How about local crime? I wish I had data for Los Altos going back to 1960, but this is the best I can do: Bottom line, property crime went up a little, down a little, but overall is pretty much the same over the last 5 years. Property crime in this graph is...

Surveys and public comment make it clear: one of the very top concerns in Los Altos is crime. Well, crime and parking. I'm savvy enough not to wander into the parking argument. But let's talk about crime. How high is it, really? We're never going to eliminate  crime entirely. And the lower it gets, the more it's going to cost us in dollars and civil liberties to get it even lower.  If you just want the answer, skip down to "What does it all mean?" But this is a data blog! So we're going to talk about data! What is this data, anyway? Let's see if we can use some data to put our crime rates in context, so that we are all working from the same facts. If we don't have the same facts, we'll never come to a good policy. Most of the crime that Los Altans are worried about is property crime. Break-ins, theft, catalytic converters being stolen out of our driveways, and for some reason, gangs of South American organized criminals. Violent crime is less o...