Evaluating gunshot detection technology

This year, HRDAG data scientist Bailey Passmore published “Shotspotter versus Shots Fired,” in the August (2024) newsletter from New York University School of Law’s The Technology and Racial Justice Collaborative. ShotSpotter, whose parent company is now called SoundThinking, is a gunshot detection system (GDS), or technology, that uses microphones and human analysts to alert law enforcement to potential gunfire incidents.

Bailey’s analysis stemmed from data we had access to as part of our ongoing collaboration with the Invisible Institute and its director of data Trina Reynolds-Tyler. Their Pulitzer Prize-winning investigation into how Chicago Police mishandled missing persons cases included examining data from Chicago’s Office of Emergency Management & Communication. Those records include information about how quickly the 911 call versus SoundThinking report is recorded and officers dispatched—and how many officer arrivals fail to be recorded. Their analysis had two striking findings. One, that SoundThinking’s GDT is more reliably associated with dispatch under five minutes, and two, that 911 calls are more often missing a dispatch date. These findings raise interesting questions about how the city’s resources are being allocated, or should be. 

Gunshot detection technology is one example of the surveillance technology that SoundThinking markets to police forces and local governments. Wired recently reported that SoundThinking is purchasing parts of Geolitica, the company responsible for PredPol. Eight years ago, HRDAG published a critique of PredPol’s so-called predictive policing technology.

There are data and analyses used for Bailey’s article in this public GitHub repo and in Jupyter notebook.

Image: David Peters, 2024.

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