Loughborough University
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Enhancing risk assessment in police custody using a mixed methods approach

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posted on 2021-11-08, 11:10 authored by Melanie-Jane Stoneman
Each year 100,000’s of people are booked into police custody, where they can be detained without charge for up to 24 hours. Whilst in custody, the police have a duty of care and statutory obligation to ensure their safe detention. To aid them in this, national guidance provides a set of core questions around health and wellbeing that the Custody Officer should ask the detainee as part of the booking-in process, as well as recording their own observations. Part of then managing the identified risk is to place the detainee on a particular observation level which relates to how often the detainee is visited in cell. Although some research has been conducted into whether this assessment identifies risk effectively, there has been little research into how Custody Officers then analyse and evaluate the identified risk in order to apply the most appropriate observation level. Using a mixed methods approach, this thesis investigates this initial risk assessment of detainees to better understand the Custody Officer’s decision-making process. Three studies have been conducted to examine the robustness of the current process and enhance understanding around influences and significant factors that affect the analysis and evaluation of risk. The first study examines the risk assessment process as set out in national guidance, investigating the extent to which the content varies between police forces. Information from each force was collated and combined with police custody inspection reports, produced from visits conducted by HM Inspectorate of Constabulary and Fire and Rescue Services, to provide an overview of the process. The findings from this study demonstrate that the risk assessment of detainees is not consistent across police forces in England and Wales. Not only does the content differ from the national guidance, but the content and delivery differ considerably between police forces. This highlights a practical problem for police forces in ensuring that this risk assessment process is conducted to a consistent standard and ensuring the robustness of decision-making. The research then focuses on how risk is assessed and evaluated at two police forces within England using a novel approach to the research of policing practices by incorporating quantitative and qualitative research methods. In Study 2, custody record data has been statistically modelled to identify the risk factors that have the greatest influence on observation level using logistic regression, decision trees and discriminant analysis. This robust approach enables the results from these multivariate methods to be compared to determine if a core set of influencing variables can be identified. The findings from this analysis suggests that, quantitatively, there are key driving variables that Custody Officers consider in PAGE ii their decision-making around risk and observation level such as self-harm, alcohol use/intoxication, physical injuries, the demeanour and compliance of the detainee and if the detainee needs to see a healthcare practitioner. However, these variables did not account for all the variation in observation level. This study also provided new and previously untested knowledge to suggest that known risks related to deaths in custody are significant in the decision-making process around observation level. A qualitative approach was used in Study 3 with observations of the process and interviews with Custody Officers conducted to identify influencing factors on their judgment and decision-making that could not be identified quantitively. Thematic analysis was used to analyse and group the information which identified a number of previously unrecorded factors and influences. These ranged from the busyness of the suite and staffing capacity to the Custody Officer’s risk appetite and gut instinct. These factors were considered against a risk assessment framework providing novel insight as to how they influence the identification, analysis and evaluation of risk and provide an in-depth understanding of how Custody Officer’s risk assess detainees and the influences on their subjective decision-making. The findings from these three studies have then been triangulated to provide an enhanced understanding of the process and a greater knowledge of the subjectivity that is involved in the risk assessment of detainees. The thesis found that although there are key risk factors which are taken into consideration, the lack of decision-making framework specific to assessing risk of harm to detainees leads to subjective decision-making based on a number of non-tangible factors, especially gut instinct. Using a potential model of a fast and frugal tree, a number of recommendations are provided to explore further how a decision-making framework can be developed that would incorporate the most significant risk factors as well as the judgement of the Custody Officer.


DTP - Loughborough University

Engineering and Physical Sciences Research Council

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  • Aeronautical, Automotive, Chemical and Materials Engineering


  • Aeronautical and Automotive Engineering


Loughborough University

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© Melanie-Jane Stoneman

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A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy of Loughborough University.


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Lisa Jackson ; Louise Cooke ; Sarah Dunnett

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  • PhD

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  • Doctoral

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