Exploring Some Analytical Characteristics of Finite Mixture Models

Finite mixture models have become increasingly prevalent in criminology over the past two decades. Yet there is no consensus about the appropriate criterion for model selection with finite mixture specifications. In this paper, we use simulation evidence to examine model selection criteria. Our focus is on mixture models for event count data like those often encountered in criminology. We use two indices to measure model selection performance. First, we examine how often each criterion chooses the correct specification. Then, we investigate how closely the finite mixture models selected by these criteria approximate the true mixing distribution used to simulate the event count data. We consider three sets of simulations. In the first set, the underlying model is itself a three component Poisson-based finite mixture model. In the two other sets of simulations, the underlying distribution of the Poisson rate parameter follows a continuous distribution. The analysis shows that both AIC and BIC perform well under certain sets of circumstances likely to be encountered by criminologists.

A Prospective Examination of Criminal Career Trajectories in Abused and Neglected Males and Females Followed Up into Middle Adulthood

Objectives

To examine the extent to which there are differences in the developmental course of offending among individuals with maltreatment histories, compared to nonmaltreated controls, and whether these patterns vary for males and females.

Methods

This paper uses data from a longitudinal study in which abused and neglected children (N = 908) were matched with non-maltreated children (N = 667) and followed prospectively into adulthood. Group-based trajectory modeling was conducted using official criminal history records collected through mean age 51. Patterns of criminal offending were first considered for the whole sample, with abuse status and sex included as time-stable covariates, and then separately by subgroup (control females, maltreated females, control males and maltreated males).

Results

Analyses revealed that a three-group model provided the best fit (nonoffenders, low-level chronic offenders, mid-level chronic offenders) for the overall sample. Child maltreatment and sex were significant predictors, with offenders more likely to be male and abused/neglected, compared to non-offenders. Separate analyses for the four subgroups revealed some similarities across groups in the characterization of offending trajectories, although trajectories for abused/neglected females differed significantly from trajectories for control females. Additional analyses suggest that desistance from offending may be largely a function of incapacitation due to early death, rather than imprisonment.

Conclusions

These new analyses provide evidence that child maltreatment affects patterns of offending and that there is an impact on females and males, although the impact differs by gender. Future research should build on this work by examining the mechanisms through which child maltreatment leads to differential patterns of offending throughout the life course.

     

The role of tax preparers in tax compliance

This paper assesses the influence of tax preparers on tax compliance. Using data from the Internal Revenue Service's (IRS) Taxpayer Compliance Measurement Program and an index of legal ambiguity based on Revenue Rulings, the impact of preparation mode (paid third party vs. self) on compliance at the level of the return line item is probed. The results suggest that preparers contribute to compliance by enforcing legally clear requirements but also contribute to noncompliance, as measured by the IRS, by helping taxpayers take advantage of legal ambiguity. Furthermore, an analysis of a campaign to enforce estimated tax requirements conducted by the Pennsylvania Department of Revenue suggests that tax preparers are also an important network for communicating tax agency enforcement priorities to taxpayers.An earlier version of this paper was prepared for the conference on Federal/State Research sponsored by the U.S. Internal Revenue Service.     

Micro-models of criminal careers: A synthesis of the criminal careers and life course approaches via semiparametric mixed poisson regression models,with empirical applications

Much recent research and debate in criminology have centered around how to conceptualize and model longitudinal sequences of delinquent and criminal acts committed by individuals. Two approaches dominate this controversy. One originates in thecriminal careers paradigm, which emphasizes a potentialheterogeneity of offending groups in the general population—thus leading to a distinction between incidence and prevalence of criminal offending, a focus on the onset, persistence, and desistence of criminal careers, and the possibility that criminals are a distinctive group with constant high rates of offending. Another approach places criminal events within a broader context ofstudies of the life course by explicitly substituting the conceptualization of “social events” for that of “criminal careers”. With respect to analytical models, this approach emphasizes a potentialheterogeneity of offenders with respect to order of criminal events from first to second to higher orders and thus suggests an analysis of the “risks” or “hazards” of offending by order of offense. Some extant commentaries on the criminal careers and life course approaches to conceptualizing and modeling longitudinal sequences of delinquent and criminal events committed by individuals have emphasized their differences and incompatibilities. In contrast, we apply recently developed semiparametric mixed Poisson regression techniques to develop conditions under which the two conceptual/modeling approaches are formally equivalent. We also modify the semiparametric mixed Poisson regression model of criminal careers to incorporate information on order of the delinquent/criminal event and develop an empirical application. This modification demonstrates the complementarity of the criminal careers and life course approaches, even though they have somewhat different foci.     

Locard's Principle of Exchange,Dental Examination and Fragments of Skin

The transfer of materials between victim and perpetrator was first reported by Locard in the nineteenth century. While in recent years DNA testing has been very successful in matching biological material from crime scenes to perpetrators, the following cases demonstrate that other more time‐honored methods remain useful. Two cases of lethal assault are reported where the victims had bitten their assailants resulting in fragments of the perpetrators’ skin being wedged between their teeth which were discovered during post mortem oral examinations. As the fragments were able to be matched to injuries in the perpetrators, identification was established prior to confirmatory DNA testing. In case 1 a criminal conviction for manslaughter resulted, and in case 2 the identity of the assailant was confirmed. Examination of a properly exposed and illuminated oral cavity may provide useful evidence in assault cases. These cases represent an unusual dental variant of Locard's principle.     

The Effect of Incarceration on Re-Offending: Evidence from a Natural Experiment in Pennsylvania

Objectives

This paper uses a sample of convicted offenders from Pennsylvania to estimate the effect of incarceration on post-release criminality.

Methods

To do so, we capitalize on a feature of the criminal justice system in Pennsylvania—the county-level randomization of cases to judges. We begin by identifying five counties in which there is substantial variation across judges in the uses of incarceration, but no evidence indicating that the randomization process had failed. The estimated effect of incarceration on rearrest is based on comparison of the rearrest rates of the caseloads of judges with different proclivities for the use of incarceration.

Results

Using judge as an instrumental variable, we estimate a series of confidence intervals for the effect of incarceration on one year, two year, five year, and ten year rearrest rates.

Conclusions

On the whole, there is little evidence in our data that incarceration impacts rearrest.     

Proactive Policing: a Summary of the Report of the National Academies of Sciences,Engineering, and Medicine

This paper provides a summary of our report for the National Academy of Sciences, Engineering, and Medicine on proactive policing. We find that there is sufficient scientific evidence to support the adoption of many proactive policing practices if the primary goal is to reduce crime, though the evidence base generally does not provide long-term or jurisdictional estimates. In turn, we conclude that crime prevention outcomes can often be obtained without producing negative community reactions. However, the most effective proactive policing strategies do not appear to have strong positive impacts on citizen perceptions of the police. At the same time, some community-based strategies have begun to show evidence of improving the relations between the police and public. We conclude that there are likely to be large racial disparities in the volume and nature of police–citizen encounters when police target high-risk people or high-risk places, as is common in many proactive policing programs. We could not conclude whether such disparities are due to statistical prediction, racial animus, implicit bias, or other causes.

     

Risk Factor Models for Adolescent Verbal and Physical Aggression Toward Fathers

Using a French-Canadian population-based longitudinal data set, we examine the impact of socioeconomic factors (paternal education and family structure); inherent individual factors (child gender and developmental trajectories of physical aggression from early to later childhood, problematic substance use), family environment (concurrent parent-child involvement, parental problematic substance use), and prospective and concurrent parenting process variables (mean parental supervision at puberty, concurrent punishment practices) as predictors of adolescent-directed aggression against fathers (in the last 6 months). A childhood behavioral pattern characterized by physical aggression showed the highest risk of adolescent-directed verbal and physical aggression toward fathers, regardless of sex. In terms of parental practices, verbal (and not corporal) punishment in the last 6 months significantly predicted aggression toward fathers. A childhood life-course of violence is likely to culminate in aggression toward fathers during adolescence. Beyond this risk, it seems that harsh verbal punishment by parents builds up the odds of child-directed aggression against fathers.