De-escalation technology: the impact of body-worn cameras on citizen-police interactions

Last registered on September 22, 2021

Pre-Trial

Trial Information

General Information

Title
De-escalation technology: the impact of body-worn cameras on citizen-police interactions
RCT ID
AEARCTR-0007785
Initial registration date
September 21, 2021
Last updated
September 22, 2021, 5:30 PM EDT

Locations

Primary Investigator

Affiliation
University of Warwick

Other Primary Investigator(s)

PI Affiliation
Queen Mary University of London
PI Affiliation
London School of Economics
PI Affiliation
PUC-Rio

Additional Trial Information

Status
Completed
Start date
2018-09-03
End date
2018-12-10
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
We implemented a RCT of body-worn cameras in the state of Santa Catarina, Brazil. In partnership with the State Military Police (PMSC), we randomized the roster of 450 police officers with public facing duties across 5 police precincts to either a treatment or a control group in a 1:3 ratio. To estimating learning effects, we also randomly provided blackout days, in which no officers would be allowed to wear cameras during their shifts. Our analysis is done at the police dispatch/event level, in which police-citizen interactions unfold.
External Link(s)

Registration Citation

Citation
Barbosa, Daniel et al. 2021. "De-escalation technology: the impact of body-worn cameras on citizen-police interactions." AEA RCT Registry. September 22. https://doi.org/10.1257/rct.7785-1.0
Experimental Details

Interventions

Intervention(s)
We implemented a RCT of body-worn cameras in the state of Santa Catarina, Brazil. In partnership with the State Military Police (PMSC), we randomized the roster of police officers (approx. 450) with public facing duties across 5 police precincts to either a treatment or a control group in a 1:3 ratio. We also randomly provided blackout days, in which no officers would be allowed to wear cameras during their shifts. Our analysis is done at the police dispatch/event level, in which police-citizen interactions unfold.
Intervention Start Date
2018-09-03
Intervention End Date
2018-12-10

Primary Outcomes

Primary Outcomes (end points)
(i) Indicator if the event generated a police report; (ii) Indicator if there was any victim reported; (iii) "Citizen Behavior"; (iv) Use of Force; (v) Indicator for Arrests and Handcuffs; (vi) Inverse covariance-weighted Index combining (iii), (iv) and (v)
Primary Outcomes (explanation)
Citizen Behavior is an indicator if there was any charges of contempt, disobedience or resistance towards officers; Use of Force is an indicator if there was any deployment of physical, non-lethal or lethal force by the police; Inverse covariance-weighted Index follow Anderson (2008)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
- BWC Assignment: From the roster of 450 sworn police officer with public facing duties we stratified them into blocks based on (i) precinct, (ii) officer main activity type (tactical, preventive or ostensive operations), (iii) above/below median rank, (iv) above/below number of previous internal investigations and (v) gender. We further collapse blocks with less than 3 officers, resulting in a total number of 40 stratifications blocks. We then randomly allocated 1/3 of officers inside each block to the treatment group.

- Blackout Days: We stratified the experimental period days based on days of the week and randomly selected days that BWC would not be available for all officers in the police precincts. In this way, we ensure that we have shifts (12h each) in which treatment is not administered to any officer during those periods, either by directly using BWCs or by patrolling with officers wearing BWCs.
Experimental Design Details
Randomization Method
Computer Randomization
Randomization Unit
(1) BWC assignment at the officer level; (2) Blackout day assignment at two 12 hour shift (1 day)
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
40 stratification blocks
Sample size: planned number of observations
180 events per day on average before the officer level randomization x 98 experimental days = 17640 events
Sample size (or number of clusters) by treatment arms
301 treated officers, 149 control officers. 24 blackout days, 74 no-blackout days.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
IRB

Institutional Review Boards (IRBs)

IRB Name
Study has received IRB approval. Details not available.
IRB Approval Date
Details not available
IRB Approval Number
Details not available

Post-Trial

Post Trial Information

Study Withdrawal

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Intervention

Is the intervention completed?
No
Data Collection Complete
Data Publication

Data Publication

Is public data available?
No

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials