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1. Introduction. 2. What is police corruption?. 3. The causes of police corruption. 4. Corruption control. Systematic reviews and meta-analysis
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1. Introduction
Corruption in various jurisdictions Aim and methodology
The report
2. What is police corruption?
Corrupt activities
The problem of definition A question of ethics?
The ‘slippery slope’ to ‘becoming bent’ Summary
3. The causes of police corruption
A few bad apples?
The causes of corruption Drug-related police corruption
4. Corruption control
Human resource management Anti-corruption policies Internal controls
The external environment and external controls
Possible unintended consequences of corruption control
5. Conclusion: Toward ‘ethical policing’
In the first chapter, Newburn provides a brief outline of his methodology, reported to cover ‘the main English language literature on the issues of police corruption and police ethics over the last 20 years’, drawn from sociology, criminology and ‘official inquiries from the US and Australia’ (1999: 2). More recent literature reviews, such as Myhill’s (2012) study of community engagement in policing, tend to have more detailed methodology sections, particularly with respect to sam- pling, setting out the literature search strategies in terms of keywords employed and databases searched, number of sources included and the inclusion criteria.
The main weakness of narrative reviews is their inability to demonstrate an absence of reviewer subjectivity or bias. In other words, because of their breadth, they do not necessarily state how sources have been identified, how fully the litera- ture has been appraised or how sources have been included or excluded. In a student dissertation or thesis, it is good practice to include an overview of the litera- ture review methodology employed.
Systematic reviews and meta-analysis
A type of review that became popular in medical and health services research in the 1990s, and took hold in the social sciences this century, is the systematic review. Reflecting the growing popularity of systematic reviews in the social sciences, there are now several publications dedicated to this research methodology (see, for exam- ple, Boland et al., 2017 and Gough et al., 2017). Now preferred in some areas of criminology, it is typically used for the purpose of evaluating the effectiveness of an intervention as evidenced by past studies, in order to support future evidence-based policy making. Such reviews address common failures of social sciences and other disciplines to produce cumulative knowledge on given hypotheses, since studies carried out into a similar issue have frequently provided differing results, and lit- erature reviews taking account of a range of separate studies have not always been systematic in their approach. According to Pawson (2006: 18), systematic reviews have also come to be favoured over evaluation studies as a means of feeding into policy-making, on the basis that ‘in order to inform policy, the research must come before the policy’.
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Systematic reviews are intended to bring together the most directly relevant
and rigorous evaluations that have been conducted on a particular topic, employ- ing transparent and systematic criteria for searching the available literature, evaluating the suitability of each source for inclusion in the review, and synthesiz- ing the results. Such literature reviews are designed to offer a rigorous and replicable approach to reviewing the literature, for the purpose of eliminating the subjectivities of reviewer bias and addressing the uncertainty as to whether all the evidence has been identified and evaluated. The approach followed in the system- atic review is described as fully and systematically as would be any empirical research.
The Campbell Collaboration is an international research network that pro- duces systematic reviews of evaluation research on specific social policy interventions in order to inform policy making, and which has been instrumental in raising the status of the approach within criminology. It is a sibling organiza- tion to the longer-established and healthcare-focused Cochrane Collaboration, and includes a Crime and Justice Coordinating Group among its thematic sub- groups. On its website, the Campbell Collaboration outlines four components of a systematic review:
1. Clear inclusion/exclusion criteria
2. An explicit search strategy
3. Systematic coding and analysis of included studies
4. Meta-analysis (where possible).
Box 3. 4 provides a second extract from the contents page of a literature review, in this case a systematic review by Farrington and Welsh (2002: iii) of research evaluating
the effects of street lighting on crime, once again conducted for the UK Home Office. In this example, the parameters of the literature were much narrower than those employed by Newburn (1999). Rather than interrogating general literature on street lighting and crime, the focus was on establishing the combined results of 13 American and British studies, selected by means of an exhaustive literature search process and the application of explicit and rigorous inclusion criteria. All of the chosen studies adopted the same general strategy of evaluating the direct relation- ship between interventions to improve street lighting in the study areas and crime levels in those areas, for the purpose of informing crime-prevention policy making. Aggregating the statistical results by means of a meta-analysis, Farrington and Welsh were able to draw the conclusion that ‘improved street lighting was followed by a decrease in crime’ (2002: 39).
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The structure of this systematic review differs markedly from Newburn’s (1999) nar- rative review. The general literature is briefly summarized in the introductory background chapter (Chapter 1) to provide a mini narrative review, and then the review methods are explained in much greater detail in a distinct methods chapter (Chapter 2). The findings in this much more focused study are set out in a single chapter (Chapter 3) and, like the Newburn review, it ends with a conclusion chapter (Chapter 4).
The strengths of the systematic review are also its limitations, emphasizing the very different purposes of the two types of literature review. The prescriptive approach required of a systematic review precludes the comprehensive coverage of the literature that, in the case of the Farrington and Welsh (2002) study, would include a detailed exposition of the relevant theoretical explanations, such as envi- ronmental and situational theories of crime, and a discussion of the causal links between street lighting and crime that are proposed within the literature. Both topics are discussed briefly by Farrington and Welsh in their introductory chapter, whereas a narrative review would give these themes far more weighting and serve as a more general appraisal of the topic area.
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A systematic review can, however, be a huge undertaking, generating tens of thousands of sources that need to be filtered, depending on the scope of the topic. Joliffe (2008) describes using the approach in his doctoral research, which sought to establish whether there was empirical support for the relationship between empathy and offending. The field of study can of course be narrowed. Lö sel (2008) gives the example of a broad definition (sex offender treatment) versus a narrow one (hormonal treatment of adult child molesters), the former of which will generate a large body of results and perhaps one that is too large. Yet, he argues, the latter approach may produce only a limited number of studies and present dilemmas of inclusion and exclusion of those identified, some of which may be limited in their methodological rigour. An alternative approach based on similar principles is a ‘rapid evidence assessment’, as employed by Joliffe and Farrington (2007) in relation to the impact of mentoring on re-offending, in which the methods used in a systematic review are applied within a restricted time frame.
Petrosino et al. (2003) and Farrington and Welsh (2005) offer guidance on
employing a systematic review methodology in criminological research. Examples of systematic reviews can be found on the websites of the Campbell Collaboration, and the Swedish National Council for Crime Prevention (Brottsfö rebyggande rå det – Brå ), on such topics as risk factors in terrorism radicalization, sex offender treatment, bul- lying prevention in schools and neighbourhood watch.
A ‘meta-analysis’ (a term coined by Glass in 1976) is an optional component of a systematic review, and comprises a statistical synthesis of the findings. This is achieved by identifying a common measure of effect size, such as a standard- ized mean difference (a way of standardizing a range of outcomes measured on different scales) or correlation coefficient (showing the relationship between
variables demonstrated by the combined results). Criminological examples are provided by Andrews et al. (1990) on the effectiveness of correctional treatment and Gore and Drugs Survey Investigators’ Consortium (1999) on young people’s illicit drug use.
Finally, a related movement is the emergence of the ‘qualitative meta-synthesis’ (including its sub-genre, ‘meta-ethnography’), advocating synoptic interrogations of literature according to systematic methods to ensure comprehensiveness and eliminate researcher bias. Like the systematic review, its origins are in health services research, with the objective of enhancing evidence-based decision making.
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