Abstract
Objectives
To examine whether the introduction of an acoustic gunshot detection system (AGDS) allied to CCTV cameras increased the frequency of confirmed incidents of shots fired by bringing to notice gunfire events in public places that were not reported by the public.
Methods
In a partially block-randomized experimental design, 17 acoustic sensors were co-located with CCTV cameras in a balanced design that matched the sensor camera sites with equivalent control locations. Gunshot-related incidents within 900 ft of both intervention and control sites for 8 months pre- and post-intervention were examined with multilevel negative binomial regression models.
Results
After implementation of the AGDS, gunshot incidents increased by 259%; however, there was no significant increase in the number of confirmed shootings.
Conclusions
The AGDS did not significantly affect the number of confirmed shootings, but it did increase the workload of police attending incidents for which no evidence of a shooting was found. While awaiting technological improvements and considering the operational goals, police departments may wish to reconsider the current operational plan and objective of an AGDS.
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Notes
While the preliminary data capture for purposes of the cluster analysis was a distance of 800 ft, for the actual implementation, the effective range of the acoustic sensors was subsequently expanded by 100 ft on the advice of technical specialists familiar with the AGDS.
A likelihood ratio test did not explicitly favor the multilevel model over a single level negative binomial model for the “incidents” outcome; however, because the multilevel negative binomial model was shown to be a significant improvement for the “founded” model (LR test \( {\overline{\chi}}^2=4.52,P=0.017 \)), it is used here for consistency. There were no substantial differences in outcomes between the models.
Dent is not associated with the system and his source for this comment is unclear; however, he does quote Mike Vidro, the public safety special projects manager for the police department, who was integral to the introduction of the AGDS sensors and who kindly liaised at length with the authors for this project.
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Ratcliffe, J.H., Lattanzio, M., Kikuchi, G. et al. A partially randomized field experiment on the effect of an acoustic gunshot detection system on police incident reports. J Exp Criminol 15, 67–76 (2019). https://doi.org/10.1007/s11292-018-9339-1
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DOI: https://doi.org/10.1007/s11292-018-9339-1