Crime Score as Weapon of Math Destruction

What is Walk Score/Crime Grade?

In the past 10 years Walk Score has gone from a cool GIS startup to a popular Redfin widget, helping people plan their moves and real estate purchases based on a neighborhood’s perceived walkability. Recently Walk Score has begun beta testing Crime Grade, a measure of crime risk near an address.

How does it work?

Walk Score uses a patented system to score locations by amenity access and pedestrian friendliness including population density, block length and intersection density (Walk Score Methodology). Crime Grade‘s letter grade is calculated using a location’s per capital crime rate ranked with other rates around the city.

Why is it problematic?

Jeff Speck’s General Theory of Walkability states:

“…to be favored, a walk has to satisfy four main conditions: it must be useful, safe, comfortable, and interesting.”

While Walk Score does a pretty good job of measuring useful walks with distance to amenities, it is less effective at measuring a walk’s safety, much less the more subjective aspects of comfort and interest.

Crime Grade is scored based on reported crime: crimes reported to the local police. This is potentially very different from the measure most important to potential walkers; perceived safety. While it is useful to know what crimes are reported to the police, what keeps walkers from a neighborhood is really their perception of what crimes are committed there. Like many crime statistics, measures of perceived crime and disorder are very connected to the racial and economic demographics of the neighborhood (Sampson and Raudenbush 2004). In fact, the most powerful predictor of perceived disorder is neighborhood demographics, stronger than observed disorder and even reported crime (ibid). Crime Grade has the potential to become another in a long line of Weapons of Math Destruction, algorithms that hard code our implicit biases about race and class with potentially drastic consequences.

Potential Solutions

My research attempts to tease out some of the racial, gender and class dynamics in perceived walkability. Using data collected about people’s perceptions of sidewalk interactions I intend to analyze racial/gender and class differences.


Works in Progress III: Crime-Avoidant Walking Directions

The most recent project I’ve been thinking about is a map app that occurred to me while I was walking from Cal Train to BART in San Francisco. I stumbled upon a supremely sketchy block full of vagrants and smelling of urine. Returning back from a trip, everything of value that I owned was in my backpack and I just prayed I wouldn’t get mugged. I wondered to myself if GoogleMaps took crime stats into account when giving walking directions. As a GIS analyst myself it struck me this seemed to me like a fairly do-able project.

A simple google search yielded a number of articles from early 2012 when Microsoft filed a patent for this type of technology. The technology was controversial because a map that avoids crime-ridden areas of most cities seems like a racist map. If the crime data is pin-pointed and updates dynamically I don’t think there should be too much of a problem with racial repercussions, but it’s something to keep thinking about.

I wondered whether or not Microsoft’s mapping software (BingMaps) was now taking weather or crime stats into account. Since the patent is public record, I emailed one of the names on the patent to ask about the patent and see if I could be of any help. He said “I don’t know of any work at Microsoft to exploit this idea. I am not planning to do anything in this area.” I’ll run the idea by my geonerds this week, see if there are any next steps.

Apple Maps – Old News

*I’ve decided to change my blogpost day to Monday and shorten the posts while I’m in school.

It’s been a few months since Apple announced it would they would create their own map app, no longer relying on google maps. I’ve linked to a few articles below. I read somewhere (I can’t remember where) that apple has hired real cartographers to run their maps department while google hired computer programmers. I’m curious to see how this turns out.

With the advent of GoogleMaps everyone became an amateur cartographer. But in order to make maps that display more specific information you need to be able to use a program like ArcGIS and you need some rudimentary knowledge of programming. Is this a problem? In my Human Computer Interaction (HCI) class we’re learning that it is never the User’s fault if they can’t get something to work. Is it okay for some fields to require specialist knowledge? Why/Why not?

On a personal level I’m trying to figure out if it’s worth it to learn enough about computers and programming to write my own programs or whether I just need to learn how to use the crappy existing ones well enough for my needs.