Bias by Proxy

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 bias by proxy.

Many departments in California, not to mention the state RIPA Board, have looked at the data surrounding bias by proxy, and the steps that can be taken to mitigate it.

The Data

A friend recently asked me if the RIPA data had anything to say about Bias by Proxy in Los Altos. Fortunately, there is a field in the data called "Call for Service." If "Call for Service" is "True" then that means that someone requested the police to come, and as a result the police made the stop. 

If we look at the number of stops made by the Los Altos Police, separated by whether the stop was a response to a Call for Service or not, we can look at the racial distribution of those stops.

The top bar shows stops where there was no call, the police made the stop of their own accord. The second bar shows stops that were the result of a call for service, and the bottom bar shows the population of Los Altos. This data runs between February 2021 and June 2023. The analysis can be found here, and all the code can be found here.

The Interpretation

Immediately we see that the orange bar, representing Black people, is much larger in the "Call" bar than in the "No Call" bar. In fact, a stop made in response to a call is 3.8 times more likely to be a Black person than a stop initiated by police. That's a pretty strong indicator that we do have an issue with Bias by Proxy in Los Altos.

Interestingly, though, the ratio goes the other way when it comes to Hispanic people. Hispanics are more likely to be stopped by police without a call than with one. We don't know the reason for that; perhaps residents of Los Altos expect to see Hispanic gardeners and maintenance people, so they are less likely to call.

While there does seem to be bias by proxy, this doesn't let the police off the hook! Black people are stopped by the police of their own accord much more frequently than would be expected from their population. Notice how small the orange bar is in the Population bar, even compared to the Call bar.  We've talked about this problem before, as well as some of the data challenges involved.

The Path Forward

There are steps that both the police and our community can take to improve on this problem. The Davis Police Department provides this handy chart for citizens:

The Department, the City, and all of us have a role in prompting our fellow citizens to be looking for suspicious activity rather than  suspicious people. 

In addition, many departments have adopted procedures for taking in calls from the public that are designed to counter bias by proxy, asking many of the questions that appear in that cartoon. The state RIPA board issues a report every year with recommended best practices. The 2021 report in particular gives recommendations to departments on how they can counter bias by proxy. These recommendations should be adopted, to the extent they haven't already been.

Conclusion

We do have a problem with bias by proxy in Los Altos, but there are a lot of concrete steps we can take to improve:

• Adopt the state RIPA Board recommendations to minimize bias-by-proxy
• Develop a protocol for when police receive calls of suspicious persons, designed to minimize bias by proxy
• Educate and encourage our community to think about the difference between suspicious activity and suspicious people.