David Thornton

Improving Risk Assessments for Sex Offenders: A Comparison of Three Actuarial Scales

The study compared the predictive accuracy of three sex offender risk-assessment measures: the RRASOR (Hanson, 1997), Thorntons SACJ-Min (Grubin, 1998), and a new scale, Static-99, created by combining the items from the RRASOR and SACJ-Min. Predictive accuracy was tested using four diverse datasets drawn from Canada and the United Kingdom (total n = 1301). The RRASOR and the SACJ-Min showed roughly equivalent predictive accuracy, and the combination of the two scales was more accurate than either original scale. Static-99 showed moderate predictive accuracy for both sexual recidivism (r = 0.33, ROC area = 0.71) and violent (including sexual) recidivism (r = 0.32, ROC area = 0.69). The variation in the predictive accuracy of Static-99 across the four samples was no more than would be expected by chance.

Psychopathy and the predictive validity of the PCL-R: an international perspective.

Its controversial past notwithstanding, psychopathy has emerged as one of the most important clinical constructs in the criminal justice and mental health systems. One reason for the surge in theoretical and applied interest in the disorder is the development and widespread adoption of reliable and valid methods for its measurement. The Hare PCL-R provides researchers and clinicians with a common metric for the assessment of psychopathy, and has led to a surge in replicable and meaningful findings relevant to the issue of risk for recidivism and violence, among other things. Most of the research thus far has been based on North American samples of offenders and forensic psychiatric patients. We summarize this research and compare it with findings from several other countries, including England and Sweden. We conclude that the ability of the PCL-R to predict recidivism, violence, and treatment outcome has considerable cross-cultural generalizability, and that the PCL-R and its derivatives play a major role in the understanding and prediction of crime and violence.

Assessing Risk for Sexual Recidivism: Some Proposals on the Nature of Psychologically Meaningful Risk Factors:

Risk assessment and treatment for sexual offenders should focus on individual characteristics associated with recidivism risk. Although it is possible to conduct risk assessments based purely on empirical correlates, the most useful evaluations also explain the source of the risk. In this review, the authors propose that the basic requirements for a psychologically meaningful risk factor are (a) a plausible rationale that the factor is a cause of sexual offending and (b) strong evidence that it predicts sexual recidivism. Based on the second of these criteria, the authors categorize potential risk factors according to the strength of the evidence for their relationship with offending. The most strongly supported variables should be emphasized in both assessment and treatment of sexual offenders. Further research is required, however, to establish causal connections between these variables and recidivism and to examine the extent to which changes in these factors leads to reductions in recidivism potential.

Distinguishing and Combining Risks for Sexual and Violent Recidivism

Abstract: A two‐dimensional risk assessment system for sexual offenders was created that can classify them for risk of sexual recidivism, risk of nonsexual violent recidivism, and the composite risk of reconviction for sexual or nonsexual assaults. Receiver operating characteristic (ROC) analyses of separate follow‐up samples were used for cross‐validation. The system is easier to score than Static‐99, and substantially easier to score than the VRAG or SORAG, while yielding comparable predictive accuracy in cross‐validation samples with follow‐ups from 2 years to 19 years. ROC AUC coefficients between .74 and .81 were found for the different scales and samples.

Improving the Predictive Accuracy of Static-99 and Static-2002 With Older Sex Offenders: Revised Age Weights

Actuarial risk assessment scales and their associated recidivism estimates are generally developed on samples of offenders whose average age is well below 50 years. Criminal behavior of all types declines with age; consequently, actuarial scales tend to overestimate recidivism for older offenders. The current study aimed to develop a revised scoring system for two risk assessment tools (Static-99 and Static-2002) that would more accurately describe older offenders’ risk of recidivism. Using data from 8,390 sex offenders derived from 24 separate samples, age was found to add incremental predictive validity to both Static-99 and Static-2002. After creating new age weights, the resulting instruments (Static-99R and Static-2002R) had only slightly higher relative predictive accuracy. The absolute recidivism estimates, however, provided a substantially better fit for older offenders than the recidivism estimates from the original scales. We encourage evaluators to adopt the revised scales with the new age weights.

Risk Assessment of Sex Offenders

What is needed to carry out a thorough risk assessment of an ex-offender? This article describes four major components: (a) a functional analysis of the offense process in order to determine how the offenders’ problems contributed to their offending and to identify the modus operandi used in their offense(s); (b) the application of a suitable actuarial risk predictor to assess the offender’s global level of risk; (c) identification of stable dynamic risk factors that make potential treatment targets; and (d) monitoring of acute dynamic factors that indicate offending is imminent. Professionals working with sexual offenders are often called on to assess the risk that the offenders present. These assessments are normally concerned either with the risk of further sexual offenses or with the risk of future violence of any kind. To carry out this task, the professional can use an actuarial risk predictor or clinical judgment. Actuarial instruments are empirically derived but are essentially atheoretical in character, in that they provide no guidance on which psychological risk factors underlie risk and hence no indication of how risk can be reduced or when such a reduction in risk has taken place (e.g., through successful treatment). Clinical judgment may allow a decision to be made at an ideographic level but has until recently been both idiosyncratic and unfounded in the research. In the last few years very real attempts have been made to draw these approaches together, both in general risk assessment (i.e., Andrews & Bonta, 1995) and its application to sexual offenders (Beech, Erikson, Friendship, & Hanson, 2002; Thornton, 2002).

Process variables in the treatment of sexual offenders: A review of the relevant literature

The present review considers the relevance of process issues for the treatment of sexual offenders. The general literature on psychotherapy indicates that the therapists style, the clients perceptions of the therapist, and the alliance between client and therapist, all influence treatment effectiveness. From our review of this literature, and the far less voluminous research on these issues by cognitive behavior therapists, we draw implications for enhancing the effectiveness of treatment of sexual offenders. We also make suggestions for research on process variables in the treatment of these offenders.

Therapist characteristics in the treatment of sexual offenders: Tentative data on their relationship with indices of behaviour change

The present study examined the relationship between reliably identified therapist characteristics and treatment-induced changes in sexual offender treatment programmes in English prisons. The results indicated that 10 therapist features predicted beneficial changes in coping skills, perspective-taking, and relationship difficulties. A confrontational style, on the other hand, was negatively related to increased competence in coping. The results are discussed in terms of their research and clinical implications.

Absolute Recidivism Rates Predicted By Static-99R and Static-2002R Sex Offender Risk Assessment Tools Vary Across Samples A Meta-Analysis

There has been considerable research on relative predictive accuracy (i.e., discrimination) in offender risk assessment (e.g., Are high-risk offenders more likely to reoffend than low-risk offenders?), but virtually no research on the accuracy or stability of absolute recidivism estimates (i.e., calibration). The current study aimed to fill this gap by examining absolute and relative risk estimates for certain Static sex offender assessment tools. Logistic regression coefficients for Static-99R and Static-2002R were combined through meta-analysis (8,106 sex offenders; 23 samples). The sexual recidivism rates for typical sex offenders are lower than the public generally believes. Static-99R and Static-2002R both demonstrated remarkably consistent relative predictive accuracy across studies. For both scales, however, the predicted recidivism rates within each risk score demonstrated large and significant variability across studies. The authors discuss how the variability in recidivism rates complicates the estimation of recidivism probability in applied assessments.

Predicting Recidivism Amongst Sexual Offenders: A Multi-site Study of Static-2002

The predictive accuracy of Static-2002 (Hanson & Thornton, Notes on the development of Static-2002 (Corrections Research User Report No. 2003-01), 2003) was examined in eight samples of sexual offenders (five Canadian, one U.S., one U.K., one Danish; total sample of 3,034). Static-2002 showed moderate ability to rank order the risk for sexual, violent and general (any) recidivism (AUCs of .68, .71, and .70, respectively), and was more accurate than Static-99. These findings support the use of Static-2002 in applied assessments. There were substantial differences across samples, however, in the observed sexual recidivism rates. These differences present new challenges to evaluators wishing to use actuarial risk scores to estimate absolute recidivism rates.