Comparing Conventional and Machine-learning Approaches to Risk Assessment in Domestic Abuse Cases

Jeffrey Grogger, Ria Ivandic, Tom Kirchmaier

Research output: Working paperResearch

Abstract

We compare predictions from a conventional protocol-based approach to risk assessment with those based on a machine-learning approach. We first show that the conventional predictions are less accurate than, and have similar rates of negative prediction error as, a simple Bayes classifier that makes use only of the base failure rate. A random forest based on the underlying risk assessment questionnaire does better under the assumption that negative prediction errors are more costly than positive prediction errors. A random forest based on two-year criminal histories does better still. Indeed, adding the protocol-based features to the criminal histories adds almost nothing to the predictive adequacy of the model. We suggest using the predictions based on criminal histories to prioritize incoming calls for service, and devising a more sensitive instrument to distinguish true from false positives that result from this initial screening.
Original languageEnglish
Place of PublicationLondon
PublisherCentre for Economic Performance (CEP), London School of Economics and Political Science
Number of pages13
Publication statusPublished - Feb 2020
SeriesCEP Discussion Paper
Number1676

Keywords

  • Domestic abuse
  • Risk assessment
  • Machine learning

Cite this

Grogger, J., Ivandic, R., & Kirchmaier, T. (2020). Comparing Conventional and Machine-learning Approaches to Risk Assessment in Domestic Abuse Cases. London: Centre for Economic Performance (CEP), London School of Economics and Political Science. CEP Discussion Paper, No. 1676
Grogger, Jeffrey ; Ivandic, Ria ; Kirchmaier, Tom. / Comparing Conventional and Machine-learning Approaches to Risk Assessment in Domestic Abuse Cases. London : Centre for Economic Performance (CEP), London School of Economics and Political Science, 2020. (CEP Discussion Paper; No. 1676).
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Grogger, J, Ivandic, R & Kirchmaier, T 2020 'Comparing Conventional and Machine-learning Approaches to Risk Assessment in Domestic Abuse Cases' Centre for Economic Performance (CEP), London School of Economics and Political Science, London.

Comparing Conventional and Machine-learning Approaches to Risk Assessment in Domestic Abuse Cases. / Grogger, Jeffrey; Ivandic, Ria; Kirchmaier, Tom.

London : Centre for Economic Performance (CEP), London School of Economics and Political Science, 2020.

Research output: Working paperResearch

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N2 - We compare predictions from a conventional protocol-based approach to risk assessment with those based on a machine-learning approach. We first show that the conventional predictions are less accurate than, and have similar rates of negative prediction error as, a simple Bayes classifier that makes use only of the base failure rate. A random forest based on the underlying risk assessment questionnaire does better under the assumption that negative prediction errors are more costly than positive prediction errors. A random forest based on two-year criminal histories does better still. Indeed, adding the protocol-based features to the criminal histories adds almost nothing to the predictive adequacy of the model. We suggest using the predictions based on criminal histories to prioritize incoming calls for service, and devising a more sensitive instrument to distinguish true from false positives that result from this initial screening.

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Grogger J, Ivandic R, Kirchmaier T. Comparing Conventional and Machine-learning Approaches to Risk Assessment in Domestic Abuse Cases. London: Centre for Economic Performance (CEP), London School of Economics and Political Science. 2020 Feb.