International Journal of Offender Therapy and Comparative Criminology recent issues

Editorial: Media Consideration of Sex Offenders: How Community Response Shapes a Gendered Perspective

Frei, A. — 2008-08-26

The Exclusion-Inclusion Spectrum in State and Community Response to Sex Offenders in Anglo-American and European Jurisdictions

Petrunik, M., Deutschmann, L. — 2008-08-26

Continental European and Anglo-American jurisdictions differ with regard to criminal justice and community responses to sex offenders on an exclusion–inclusion spectrum ranging from community protection measures on one end to therapeutic programs in the middle and restorative justice measures on the other end. In the United States, populist pressure has resulted in a community protection approach exemplified by sex offender registration, community notification, and civil commitment of violent sexual predators. Although the United Kingdom and Canada have followed, albeit more cautiously, the American trend to adopt exclusionist community protection measures, these countries have significant community-based restorative justice initiatives, such as Circles of Support and Accountability. Although sex offender crises have recently occurred in continental Europe, a long-standing tradition of the medicalization of deviance, along with the existence of social structural buffers against the influence of victim-driven populist penal movements, has thus far limited the spread of formal community protection responses.

The Gottfredson-Hirschi Critiques Revisited: Reconciling Self-Control Theory, Criminal Careers, and Career Criminals

DeLisi, M., Vaughn, M. G. — 2008-08-26

Revisiting Gottfredson and Hirschi's critiques of criminal career research, the current study views low self-control as being analogous to criminal propensity and examines its predictive validity of career criminality among 723 incarcerated delinquent youths. Four key findings emerged. Compared to noncareer offenders, career criminals had significantly lower levels of self-control. Second, youths scoring one standard deviation above the mean on the Self-Control Scale had an odds ratio of 5.36 of becoming a career criminal. Third, self-control predicted career criminal membership with receiver operator characteristic-area under the curve sensitivity accuracies between 74% and 87%, suggesting that self-control is a potentially useful screening device for chronic criminality. Fourth, low self-control was overwhelmingly the strongest predictor of career criminality and far exceeded the impact of age, race, ethnicity, gender, socioeconomic status, mental illness, attention deficit hyperactivity disorder diagnosis, and trauma experience. Further integration between self-control and criminal career research is urged.

A General Test of Self-Control Theory: Has Its Importance Been Exaggerated?

Cretacci, M. A. — 2008-08-26

Self-control theory has been tested for 2 decades. However, mixed results and measurement problems have made it difficult to ascertain its true utility. This study addresses recent concerns and includes variables such as risk, consequences, criminal opportunity, an interaction term, and bond controls in one complete test. It also addresses self-control's ability to explain different forms of crime and whether the support that it has garnered has been exaggerated. Results of both cross-sectional and semilongitudinal tests indicate that self-control significantly predicts a higher probability of involvement in property and drug crime but is virtually silent in its ability to explain violence. Furthermore, it can be tentatively stated that support for the theory wanes over time. Finally, neglected concepts such as opportunity, risk, consequences, and bond controls may be important to the theory's ability to explain crime, and further negligence of these concepts may hamper a true understanding of its impact.

The Relationship of Self-Regulation and Aggression: An Empirical Test of Personality Systems Interaction Theory

Ross, T., Fontao, M. I. — 2008-08-26

On the basis of personality systems interaction (PSI) theory, the authors examine self-regulation, conflict behaviour, behavioural resources, and personality disorders in a sample of 83 male offenders and explore the role self-regulatory variables play with respect to aggressive behaviour. Although substantial correlations between self-regulatory functions and aggressive behaviour were found, these variables did not predict aggression in a subsequent regression analysis with measures of self-regulation, conflict behaviour, and personality disorders as independent variables. Antisocial behaviour, behavioural self-control, and affect were among the strongest predictors of aggression. Specific predictions based on PSI theory could not be confirmed. Theoretical implications of the findings are discussed and put into relation with treatment issues of offenders.

Moral Disengagement: Relation to Delinquency and Independence From Indices of Social Dysfunction

Kiriakidis, S. P. — 2008-08-26

This article explores the relations of moral disengagement with several legal, institutional, and demographic characteristics of young offenders held in custody. The sample consisted of 152 randomly selected male young offenders from the largest young offenders' institution in Scotland. The age of the sample ranged from 16 to 21 (M = 18.9, SD =1.3). The respondents took part in a structured interview asking about several sociodemographic characteristics, and they completed the Moral Disengagement Scale. The sample in the study scored significantly higher on moral disengagement in comparison to a community sample. Higher moral disengagement was related to the offenders' families receiving help from a social worker; the expectation of an unstable living situation after custody; drug use before custody; and intention of drug use after custody. However, the lack of relation of moral disengagement to most of the social, family, school, employment, legal, and lifestyle characteristics of the sample suggests that moral disengagement is an independent variable exerting an influence on juvenile delinquent behavior over and above the social characteristics of juvenile delinquents.

Views From the Inside: Young Offenders' Subjective Experiences of Incarceration

Ashkar, P. J., Kenny, D. T. — 2008-08-26

This study examined the incarceration experiences of 16 adolescent males in a maximum-security detention facility. A semistructured interview was conducted with each detainee and recorded on audiocassette. Data were analysed using phenomenological descriptive methodology. Detainees' experiences were characterised by a prison culture of bullying, substance use, and antagonism with youth workers; inadequate service provision and a lack of rehabilitative programming; and a sense of loss through reduced autonomy and dislocation from important others. These experiences gave rise to a range of negative feelings and emotions and promoted thinking about past and future behaviours. The incarceration experience placed detainees into a state of readiness for positive change but failed to provide them with the necessary skills to effect and sustain this change. Promotion of antisocial behaviour, lack of deterrence, and insufficient rehabilitative programming were identified as factors of the incarceration setting likely to contribute to the high rates of recidivism.

Change in Treatment Has No Relationship With Subsequent Re-Offending in U.K. Domestic Violence Sample: A Preliminary Study

Bowen, E., Gilchrist, E., Beech, A. R. — 2008-08-26

In this study, data is presented from a sample of 52 male domestic violence offenders who were court mandated to attend a profeminist psycho-educational rehabilitation program in the West Midlands. The extent of both statistically and clinically significant psychological change achieved across a variety of measures (pro-domestic-violence attitudes, anger, locus of control, interpersonal dependency) assessed pre- and post-treatment, and their association with post-treatment re-offending within an 11-month follow-up period is examined. The results indicate that program completers achieved limited significant psychological change. However, the level of psychological change achieved had no association with re-offending.

Editorial: Relevant, Practical, Interdisciplinary Research: A Challenge for Us All

Schlesinger, L. B. — 2008-07-02

Power, Anger, and Sadistic Rapists: Toward a Differentiated Model of Offender Personality

Pardue, A., Arrigo, B. A. — 2008-07-02

The extant research on rapists repeatedly indicates that particular offender types can be specified. These include the power, anger, and sadistic assailants. Despite such classifications, limited empirical or anecdotal efforts have undertaken the task of exploring the personality features of each rapist type. This article endeavors to fill this gap in the literature. Using the heuristic analytical lens and the case study method, the high-profile crimes of Gilbert Escobedo (power type), Paul Bernardo (anger type), and Jeffrey Dahmer (sadistic type) are reviewed. As the article discloses, unique personality features were exhibited. Moreover, each rapist type displayed a number of convergent as well as divergent character traits. Given these findings, the article concludes with a series of summary observations relevant for future research on rape and personality as well as prospects for clinical diagnosis, treatment, and prevention.

Are the Mentally Retarded and Learning Disordered Overrepresented Among Sex Offenders and Paraphilics?

Langevin, R., Curnoe, S. — 2008-07-02

A sample of 2,286 male sex offenders and paraphilics and 241 nonsex offenders was evaluated for the prevalence of mental retardation and learning disorders, using the full Wechsler IQ scales. The sex offenders were generally of average intelligence, and the mentally retarded were not overrepresented among them, but the learning disordered were. There were no differences among sex offenders and controls in overall IQ or in the percentage of mentally retarded or learning-disordered cases, suggesting that the learning difficulties are not peculiar to sex offenders. There was a bias in referral source, with more mentally retarded, borderline-retarded, and/or learning-disordered cases being referred by the Children's Aid Society, prisons, and the Crown, suggesting that referral source may play a significant role in evaluating intelligence and mental retardation among sex offenders; but the overrepresentation of learning disorders among criminals appears to be a significant phenomenon, regardless of referral source.

Learning Disabilities and Delinquency: A Study of Israeli Prison Inmates

Einat, T., Einat, A. — 2008-07-02

Research consistently illustrates that several intellectual disabilities—namely, learning disabilities (LD), low intelligence, challenging behavior, and inadequate adaptive behavior, as well as attention deficit hyperactivity disorder (ADHD)—are considered risk factors for antisocial and criminal behavior. Although much attention has been paid to the relationship of LD, ADHD, and criminal behavior, three research topics have been overlooked: the frequency of LD with ADHD among inmates, the relationship between LD and/or ADHD and level of education among prisoners, and the connection between LD and/or ADHD and age of criminal onset. The present study examined the frequency of LD and ADHD in a sample of Israeli-born prisoners, in addition to the frequency of each category by itself, and it investigated the relationship of LD and/or ADHD, school dropout age, and onset of criminal activity.

Patterns of Substance Involvement and Criminal Behavior: A Gender-Based Cluster Analysis of Pennsylvania Arrestees

Sevigny, E. L., Coontz, P. D. — 2008-07-02

Recent drug-crime scholarship has underscored the importance of conducting disaggregated research that focuses on the consistencies and variations between subcategories of drug misuse and criminal activity and, further, how these associations may vary across sociodemographic and cultural boundaries. The research presented in this article used cluster analysis to independently classify male and female arrestees based on their arrest charges and substance-specific indicators of initiation, use, dependence, and treatment need. The data come from Pennsylvania's Substance Abuse and Need for Treatment Among Arrestees study conducted as part of the State Treatment Needs Assessment Program. Five groups were identified in both the male and female cluster analyses. The results reveal both important differences and strong similarities in the drug-crime typologies of male and female arrestees. Given these findings, implications are discussed for developing and targeting responsive treatment services that match the particular risks and needs of drug-involved offenders.

Social Control Theory and the Connection With Ideological Offenders Among Israeli Youth During the Gaza Disengagement Period

Shechory, M., Laufer, A. — 2008-07-02

The present study examined whether social control theory is capable of explaining youth's law violations in instances of conflict between the ideological religious worldview and the laws of the country in which they reside. Differences in the control factors (commitment, belief, attachment, and involvement) were examined among Israeli adolescents who took part in legal activity (n = 163) and illegal activity (n = 99) during the resistance to the Gaza evacuation. The findings indicate that the model provides a partial explanation for ideological delinquency. It was found that involvement with friends and the absence of belief in the formal legal system were associated with illegal ideology activity. Attachment to friends and parents and involvement with parents had no effect on youth's participation in illegal ideological activities.

Women in Parole: Respect and Rapport

Ireland, C., Berg, B. — 2008-07-02

Although the number of females in law enforcement has increased in recent years, research suggests that the uniquely gendered contributions of females are minimized in favor of traditional modes of law enforcement, emphasizing physical presence, authoritative commands, and demonstrative control. This research examines women in parole, using in-depth interviews with a small convenience sample of female parole agents in California. Participants discussed their experiences as parole agents from the perspective of women in a predominantly male occupation. Overwhelmingly, they emphasized traditionally associated female traits of intuition, verbal communication, and relationships, over physical tactics. Participants emphasized the importance of building respect and rapport with parolees in multiple contexts, including in the parolees' homes, with the families of parolees, and at parolees' places of employment. Participants suggested that this approach ensures their personal safety and enhances parolee compliance, especially when considering their subjective account of experiences by male parole agents.

Editorial: Sexual Violence in Prison

Noll, T. — 2008-05-06

Sexual Murderers of Children: Developmental, Precrime, Crime, and Postcrime Factors

Beauregard, E., Stone, M. R., Proulx, J., Michaud, P. — 2008-05-06

The amount of empirical research on men who commit sexual murders is scarce, and no distinction has been made between those who have victimized adults and those who have victimized children. Therefore, to better understand specifically sexual murderers of children (n = 11), comparisons were performed with a group of sexual murderers of adult women (n = 66) on developmental, precrime, crime, and postcrime factors. It appears that sexual murderers of children are more often victims of sexual abuse during childhood and present more often deviant sexual fantasies as compared to sexual murderers of women. The results show also that sexual murderers of children more often use pornography prior to crime, have contact with the victim prior to crime, and commit a crime more often characterized by premeditation, strangulation, the hiding of the body, and its dismemberment than the sexual murderers of women.

Exhibitionism: Findings From a Midwestern Police Contact Sample

Bader, S. M., Schoeneman-Morris, K. A., Scalora, M. J., Casady, T. K. — 2008-05-06

This study used a police sample to examine offense characteristics, recidivism rates, and other types of sexual offending among individuals suspected of exhibitionism. The sample consisted of 202 incidents of indecent exposure perpetrated by 106 identified individuals. Demographic information showed that one quarter of the sample had symptoms of a mental illness and one quarter had a history of substance abuse. More than 84% of the sample had other nonsexual criminal charges. Approximately 30% of the perpetrators were charged for more than one exposure incident. Masturbating during the offense, exposing to child victims, and speaking to the victim did not show any relationship to the occurrence of more sexually aggressive behaviors. However, individuals who had subsequent rape or molestation charges (16.9%) were more likely than those who did not to have had multiple exposure incidents and a history of physical assault charges.

The Prevalence of Sexual Violence in Prison: The State of the Knowledge Base and Implications for Evidence-Based Correctional Policy Making

Jones, T. R., Pratt, T. C. — 2008-05-06

The issue of prison violence and misconduct has been the subject of considerable academic attention, yet particularized areas of violent victimization within prisons have gone relatively unnoticed. One such area involves sexual violence in prisons. Scholars have argued that sexual violence contributes to a host of institutional and individual-level problems, yet the primary limitation of this body of literature is that it has been largely confined to methodologically questionable studies of prison rape prevalence. The purpose of this study, therefore, is to critically take stock of what is and what is not currently known about the prevalence of prison sexual violence. In doing so, it highlights the direction that future research should take so that evidence-based policies concerning prison sexual violence may be developed.

Husbands Who Kill Their Wives: An Analysis of Uxoricides in Contemporary Ghana

Adinkrah, M. — 2008-05-06

This article addresses the current lack of research on uxoricides in non-Western societies by examining the phenomenon in Ghana, West Africa. Analysis of data from the 60 husband—wife killings reported in a national daily newspaper reveals that jealousy and suspicion of infidelity overwhelmingly provided the basis for wife murders. The findings also indicate that assailants and victims were of low socioeconomic background and the murders predominantly occurred in the rural areas of the country. Posthomicidal suicide by the assailant occurred in about one fourth of the cases. Overall, the results demonstrate that the patterns of uxoricide in Ghana are congruous in many significant ways with those noted in Western industrialized societies. It is concluded that additional research in non-Western societies is warranted to contribute to the development of sound conclusions about and remedies for uxoricide.

Variations in Mental Health Problems, Substance Use, and Delinquency Between African American and Caucasian Juvenile Offenders: Implications for Reentry Services

Vaughn, M. G., Wallace, J. M., Davis, L. E., Fernandes, G. T., Howard, M. O. — 2008-05-06

The incarceration of young people is a growing national problem. Key correlates of incarceration among American youth include mental health problems, substance use, and delinquency. The present study uses a statewide sample of incarcerated youth to examine racial differences in African American and Caucasian juvenile offenders' outcomes related to mental health, substance use, and delinquency. The data indicate that relative to Caucasian offenders, African American offenders report lower levels of mental health problems and substance use but higher levels of delinquent behavior such as violence, weapon carrying, and gang fighting. The data further reveal that African American offenders are more likely than Caucasian offenders to be victims of violence and to experience traumatic events such as witnessing injury and death. Recognition of these patterns may help to improve postrelease services by tailoring or adapting preexisting programs to patterns of risk factors and their relative magnitudes of effect.

Global Risk Factors and the Prediction of Recidivism Rates in a Sample of First-Time Misdemeanant Offenders

Gavazzi, S. M., Yarcheck, C. M., Sullivan, J. M., Jones, S. C., Khurana, A. — 2008-05-06

This article examines the prediction of recidivism using the Global Risk Assessment Device (GRAD), a reliable and valid measure of dynamic factors associated with family characteristics, peers, mental health, substance abuse, trauma exposure, educational concerns, accountability, and health risks. Using a sample of adult caregivers of first-time misdemeanant offenders, two factors—education and accountability—were significantly associated with recidivistic behavior, supporting the use of GRAD data in correctly identifying first-time offenders who have the greatest and the least likelihood for future offending behavior. Additional analyses utilizing parent reports on African American males indicate that the GRAD provides discrimination in the prediction of recidivism in a group typically seen as being high risk simply because of their gender and race. The assessment drives intervention approach of the GRAD is discussed in terms of using reports from adults to accurately place youth into appropriate levels of supervision and treatment.

Baseline Subjective Stress Predicts 1-Year Outcomes Among Drug Court Clients

2008-05-06

Psychological stress has long been known to predict negative changes in physical and behavioral health in the general population. The same relationships have been found in research on drug abusers. In this longitudinal study, 477 clients of two Kentucky drug courts were followed for 1 year to examine the relationship between subjective stress at intake and outcomes 1 year after the baseline of this 18-month drug court program. Greater baseline subjective stress was significantly associated with poorer employment, substance use, criminal justice, and health outcomes at 1-year follow-up, even after adjusting for selected demographic characteristics and baseline levels of the outcomes of interest. If these results are replicated in these and other drug courts, then a stress reduction treatment trial within the drug court context should be attempted and evaluated.

Psychiatric Use and Utility of Divalproex Sodium in Connecticut Prisons

2008-05-06

Divalproex sodium (DVX) is used in correctional settings to treat impulsive aggression and mood lability in patients without comorbid bipolar disorder. This review of DVX use in the Connecticut Department of Correction examined the psychiatric diagnostic impression of patients prescribed DVX, the doses used, and the symptomatic and functional change over time. Clinical charts of 168 offenders treated with DVX for one or more months were randomly selected for clinical outcome review and were divided into subgroups based on clinical impression for DVX prescription. In participants without bipolar disorder (44.6%), DVX was used to target impulsivity (14.3%) and mood lability (17.3%). Clinical improvement was noted in bipolar and nonbipolar groups (p < .001). The impulsive/aggressive subgroup was the only nonbipolar subgroup in which DVX yielded clinical benefit. This symptom-driven use of DVX is associated with clinical improvement when impulsive aggression is the target symptom.

Editorial: Explaining and Treating Violent Behavior

Dussich, J. P. J. — 2008-03-05

A Test of Hirschi's Social Bonding Theory: A Comparison of Male and Female Delinquency

Ozbay, O., Ozcan, Y. Z. — 2008-03-05

In this study, Hirschi's social bonding theory is employed to identify what aspects of the theory can explain male and female delinquency and whether social bonding variables can equally explain male and female delinquency (generalizability problem) in a developing society, Turkey. The data include a two-stage-stratified cluster sample of 1,710 high school students from the central districts of Ankara, the capital of Turkey. The findings suggest that social bonding variables play a more important role for male students than for female students. Furthermore, they indicate that components of the social bonding theory can equally explain both male and female delinquent acts.

Distinguishing Juvenile Homicide From Violent Juvenile Offending

DiCataldo, F., Everett, M. — 2008-03-05

Juvenile homicide is a social problem that has remained a central focus within juvenile justice research in recent years. The term juvenile murderer describes a legal category, but it is purported to have significant scientific meaning. Research has attempted to conceptualize adolescent murderers as a clinical category that can be reliably distinguished from their nonhomicidal counterparts. This study examined 33 adolescents adjudicated delinquent or awaiting trial for murder and 38 adolescents who committed violent, nonhomicidal offenses to determine whether the two groups differed significantly on family history, early development, delinquency history, mental health, and weapon possession variables. The nonhomicide group proved more problematic on many of these measures. Two key factors did distinguish the homicide group: These adolescents endorsed the greater availability of guns and substance abuse at the time of their commitment offenses. The significance of this finding is discussed, and the implications for risk management and policy are reviewed.

The Effect of Inmates' Self-Reported Childhood and Adolescent Animal Cruelty: Motivations on the Number of Convictions for Adult Violent Interpersonal Crimes

Hensley, C., Tallichet, S. E. — 2008-03-05

Few researchers have investigated the potentially predictive power of motives for childhood and adolescent animal cruelty as it is associated with interpersonal violence in adulthood. Based on a sample of 261 inmates at medium- and maximum-security prisons in a southern state, the present study examines the relationship among several retrospectively reported motives (anger, fun, dislike, and imitation) for animal cruelty and violent crime convictions (assault, rape, and murder). Almost half reported abusing animals out of anger, whereas more than one third did so for fun. Dislike for the animal and imitation were less frequently occurring motives. Participants who abused animals at an earlier age and those who did so out of anger or for fun were more likely to repeat the offense. Regression analyses revealed that abusing an animal out of fun in their youth was the most statistically salient motive for predicting later interpersonal violence as adults.

Defense Styles of Pedophilic Offenders

Drapeau, M., Beretta, V., de Roten, Y., Koerner, A., Despland, J.-N. — 2008-03-05

This pilot study investigated the defense styles of pedophile sexual offenders. Interviews with 20 pedophiles and 20 controls were scored using the Defense Mechanisms Rating Scales. Results showed that pedophiles had a significantly lower overall defensive functioning score than the controls. Pedophiles used significantly fewer obsessionallevel defenses but more major image-distorting and action-level defenses. Results also suggested differences in the prevalence of individual defenses where pedophiles used more dissociation, displacement, denial, autistic fantasy, splitting of object, projective identification, acting out, and passive aggressive behavior but less intellectualization and rationalization.

Pervasive Developmental Disorders and Criminal Behaviour: A Case Control Study

Mouridsen, S. E., Rich, B., Isager, T., Nedergaard, N. J. — 2008-03-05

The prevalence and pattern of criminal behaviour in a population of 313 former child psychiatric in-patients with pervasive developmental disorders were studied. The patients were divided into three subgroups and compared with 933 matched controls from the general population. Age at follow-up was between 25 years and 59 years. An account of convictions in the nationwide Danish Register of Criminality was used as a measure of criminal behaviour. Among 113 cases with childhood autism, .9% had been convicted. In atypical autism (n = 86) and Asperger's syndrome (n = 114) the percentages were 8.1% and 18.4%, respectively. The corresponding rate of convictions in the comparison groups was 18.9%, 14.7%, and 19.6% respectively. Particular attention is given to arson in Asperger's syndrome (p = .0009).

The Importance of Appropriate Allocation to Offending Behavior Programs

2008-03-05

This study examined the impact on reconviction of appropriate allocation to three general offending behavior programs involving adult male offenders in the English and Welsh Probation Service. Appropriate allocation was defined by level of risk for reconviction. There were three allocation groups: too low, appropriate, and too high. Using a quasi-experimental design, the reconviction rates of offenders who were allocated to and completed a program, offenders allocated to a program who failed to start, and a comparison group were compared. It was found that the appropriateness of allocation affected reconviction independently of treatment group. Furthermore, in line with the risk principle, there was an interaction between treatment group and the appropriateness of allocation.

Aggression Control Therapy for Violent Forensic Psychiatric Patients: Method and Clinical Practice

Hornsveld, R. H. J., Nijman, H. L. I., Hollin, C. R., Kraaimaat, F. W. — 2008-03-05

Aggression control therapy is based on Goldstein, Gibbs, and Glick's aggression replacement training and was developed for violent forensic psychiatric in- and outpatients (adolescents and adults) with a (oppositional—defiant) conduct disorder or an antisocial personality disorder. First, the conditions for promoting "treatment integrity" are examined. Then, target groups, framework, and procedure are described in detail, followed by the most important clinical findings during the period 2002 to 2006. Finally, new programme developments are mentioned, with aggression control therapy as a starting point.

Effectiveness of Sex Offender Treatment for Psychopathic Sexual Offenders

Doren, D. M., Yates, P. M. — 2008-03-05

Meta-analyses have suggested that sexual offender treatment (SOT) completion is associated with lowered sexual recidivism rates for convicted sexual offenders. The paucity of properly designed studies allows for the alternative explanation of less recidivism among treated samples as reflecting that lower risk offenders disproportionately self-select into treatment. A test of the "self-selection explanation" can occur by investigating treatment effect on known high-risk offenders. Psychopathy correlates with increased sexual recidivism risk, such that an exploration of the SOT effect on psychopathic offenders could clarify the accuracy of the self-selection hypothesis. Additionally, the debated degree to which psychopaths are treatable might obtain clarification by a research review. This article examines empirical findings concerning the effectiveness of SOT for psychopathic sexual offenders. Ten studies were found to meet the minimal quality standards used, stemming from only four data sources. Shortcomings of existing research precluded clear conclusions, though trends in the data are delineated.