Random assignment in sexual offending programme evaluation: the missing method

Pages1-9
Published date12 February 2018
DOIhttps://doi.org/10.1108/JFP-08-2017-0032
Date12 February 2018
AuthorJamie S. Walton
Subject MatterHealth & social care,Criminology & forensic psychology,Forensic practice,Sociology,Sociology of crime & law,Law enforcement/correctional,Public policy & environmental management,Policing,Criminal justice
Random assignment in sexual offending
programme evaluation: the missing
method
Jamie S. Walton
Abstract
Purpose The need for random assignment in sexual offending programme evaluation is clear. Decades of
high dependence on weak-inference methodology, that of observational studies, has inhibited professional
agreement regarding the effects of programmes. Observational studies have a place in evaluation research
when more rigorous scientific designs precede them, as occurs in neighbouring fields of drug development
and health. If, however, observational studies remain the only method used to evaluate sexual offending
programmes, the field will continue to endure uncertainty with confident causal inferences regarding their
effects remaining elusive. The paper aims to discuss these issues.
Design/methodology/approach The paper takes the form of a literature review and discussion.
Findings The case for random assignment is made alongside a rebuttal of arguments against their use.
Originality/value This is an original look at the need for random assignment in sexual offending
programme evaluation taking into account existing studies and discussion topics.
Keywords Sexual offending, Selection bias, Confounding, Observational studies, Random assignment,
Sexual offending programme outcome research
Paper type Viewpoint
Sexual offending programme outcomes are interpreted in opposing ways. On the one hand,
experts have concluded that although the results are heterogeneous, the evidence shows that
cognitive-behavioural programmes can be effective at reducing recidivism (Schmucker and
Lösel, 2017). Others however have found that there is no evidence or that the evidence is too
weak to draw such a conclusion (Dennis et al., 2012; Långström et al., 2013). Rice and Harris
(2013) concluded that there is insufficient evidence to reject the null hypothesis that programmes
have no effect. In contrast, having analysed 11 meta-analyses, Kim et al. (2016) reported that
sex offender treatments can be considered as provenor at least promising(p. 105). These
experts would all agree that a strong programme evaluation study provides results that are not
impeded by systematic error. They differ however on what may be accepted as the minimum
scientific standards needed to account for error. The differing views have had a significant
bearing on how results from programme evaluation studies are interpreted.
In this paper I discuss confounding and selection bias two types of systematic error in
programme evaluation that make drawing accurate causal inferences very difficult. Confounding
occurs when the effect of a programme on recidivism is associated with an unknown third
variable (e.g. motivation to change). When confounded the effect of a programme may be
spurious because it is caused by the third variable. Selection bias on the other hand is caused by
the non-random selection of programme and control groups, and involves variables associated
with recidivism being systematically excluded from one group but not the other. Selection bias
results in a sample and outcome that does not represent the overall population about which a
conclusion is to be drawn in this case all individuals eligible for the programme. There are
two methods to addressing these errors. The first is the experimental method which uses
random recruitment and assignment to minimise both errors. The second is the observational
Received 16 August 2017
Revised 14 October 2017
Accepted 15 October 2017
The author thanks to Dr Ian Elliot
and Dr Shihning Chou for
comments on an early manuscript.
Jamie S. Walton is a Registered
Psychologist and National
Specialist Lead at Interventions
Services within the Equalities,
Interventions and Operational
Practice Group, Directorate of
Rehabilitation & Assurance,
Her Majestys Prison and
Probation Service, London,
UK.
DOI 10.1108/JFP-08-2017-0032 VOL. 20 NO. 1 2018, pp. 1-9, © Emerald Publishing Limited, ISSN 2050-8794
j
JOURNAL OF FORENSIC PRACTICE
j
PAG E 1

To continue reading

Request your trial

VLEX uses login cookies to provide you with a better browsing experience. If you click on 'Accept' or continue browsing this site we consider that you accept our cookie policy. ACCEPT