Preventing treatment spillover contamination in criminological field experiments: the case of body-worn police cameras


Type
Article
Change log
Authors
Sutherland, A 
Sherman, LW 
Abstract

ABSTRACT

Objectives: A central issue in experiments is protecting the integrity of causal identification from treatment spillover effects. The objective of this article is to demonstrate a bright line beyond which spillover of treatment renders experimental results misleading. We focus on a highly publicized recent test of police body-cameras that violated the key assumption of a valid experiment: independence of treatment conditions for each unit of analysis.
Methods: In this article, we set out arguments for and against particular units of random assignment in relation to protecting against spillover effects that violate the Stable Unit Transfer Value Assumption (SUTVA).
Results: Comparisons to methodological solutions from other disciplines demonstrate several ways of dealing with interference in experiments, all of which give priority to causal identification over sample size as the best pathway to statistical power. Conclusions: Researchers contemplating which units of analysis to randomize can use the case of police body-worn cameras to argue against research designs that guarantee large spillover effects.

Key Words: Body-worn Cameras; Unit of Randomization; Spillover Effects; SUTVA; Interference; Partial Interference; Experiments

Description
Keywords
Body-worn cameras, Unit of randomization, Spillover effects, SUTVA, Interference, Partial interference, Experiments
Journal Title
Journal of Experimental Criminology
Conference Name
Journal ISSN
1573-3750
1572-8315
Volume Title
15
Publisher
Springer Science and Business Media LLC