The Burglary Boost: A Note on Detecting Contagion Using the Knox Test

Objectives

A large body of literature in quantitative criminology finds that the spatio-temporal clustering of burglary is greater than one would expect from chance alone. This suggests that such crimes may exhibit a “boost” effect, wherein each burglary increases the risk to nearby locations for a short period. In this study, we demonstrate that standard tests for spatio-temporal dependence have difficulty distinguishing between clustering caused by contagion and that caused by changing relative risks. Therefore, any estimates of the boost effect drawn from these tests alone will be upwardly biased.

Methods

We construct an agent-based model to generate simulated burglary data, and explore whether the Knox test can reliably distinguish between contagion (one burglary increases the likelihood of another burglary nearby) and changes in risk (one area gets safer while another gets more dangerous). Incorporating insights from this exercise, we analyze a decade of data on burglary events from Washington, DC.

Results

We find that (1) absent contagion, exogenous changes in relative risk can be sufficient to produce statistically significant Knox ratios, (2) if risk is changing over time, estimated Knox ratios are sensitive to one’s choice of time window, and (3) Knox ratios estimated from Washington, DC burglary data are sensitive to one’s choice of time window, suggesting that long-run changes in relative risk are, in part, driving empirical estimates of burglary’s boost effect.

Conclusions

Researchers testing for contagion in empirical time series should take precautions to distinguish true contagion from exogenous changes in relative risks. Adjusting the time window of analysis is a useful robustness check, and future studies should be supplemented with new approaches like agent-based modeling or spatial econometric methods.

     

The Role of Site Variance in the American Judicature Society Field Study Comparing Simultaneous and Sequential Lineups

Objectives

Police departments often use photo lineups for eyewitness identification purposes. A widely adopted lineup reform designed to reduce eyewitness misidentifications involves switching from the standard simultaneous photo presentation format to a sequential format. These two lineup procedures were recently tested in the American Judicature Society (AJS) field study, which was conducted in four different police jurisdictions. The results from two phases of that investigation reached opposite conclusions as to which lineup procedure is superior, and the purpose of our current investigation was to elucidate the role of site variance in shaping those contrasting conclusions.

Methods

In previous analyses, the field study data were either (1) aggregated across all four study sites or (2) drawn from only one study site (Austin, Texas). Here, we analyze the data separately for the Austin study site, where 69 % of the eyewitnesses were tested, and the other three study sites combined, where 31 % of the eyewitnesses were tested.

Results

The results indicate significant site variance between the Austin and non-Austin study sites. In addition, the results suggest that aggregating the data across sites played a determinative role in creating the apparent disagreement about which lineup procedure is diagnostically superior.

Conclusions

Once large differences across the AJS study sites are taken into consideration, there is no longer any disagreement about which lineup procedure is superior. The simultaneous procedure is diagnostically superior to the sequential procedure, but the sequential procedure sometimes induces more conservative responding (a result that can and often does masquerade as diagnostic superiority).

     

THE CASCADING EFFECTS OF ADOLESCENT GANG INVOLVEMENT ACROSS THE LIFE COURSE*

The short‐run deleterious effects of gang involvement during adolescence have been well researched. However, surprisingly little empirical attention has been devoted to understanding how gang involvement in adolescence influences life chances and criminal behavior in adulthood. Drawing on the life‐course perspective, this study argues that gang involvement will lead to precocious transitions that, in turn, will have adverse consequences on the fulfillment of adulthood roles and statuses in the economic and family spheres. Moreover, problems fulfilling these conventional roles are hypothesized then to lead to sustained involvement in criminal behavior in adulthood. Using data from a sample of males from the Rochester Youth Development Study, results from structural equation models support the indirect link between gang membership and noncriminal and criminal outcomes in adulthood. Specifically, gang involvement leads to an increase in the number of precocious transitions experienced that result in both economic hardship and family problems in adulthood. These failures in the economic and family realms, in turn, contribute to involvement in street crime and/or arrest in adulthood. Implications for the criminal desistance process are discussed.     

Evaluation of maxillary sinus dimensions in gender determination using helical CT scanning

Gender determination is an important step in identification in forensic medicine. CT measurements of maxillary sinuses may be useful to support gender identification. This study was undertaken to study the accuracy and reliability of maxillary sinus dimensions measurement in gender classification through the use of reconstructed helical CT images. Eighty-eight patients (43 men and 45 women) with age range from 20 to 49 years were selected in this study. The width, length, and height of the maxillary sinuses in addition to the total distance across both sinuses were measured. Data were subjected to discriminant analysis for gender using multiple regression analysis. Maxillary sinus height was the best discriminant parameter that could be used to study sexual dimorphism with an overall accuracy of 71.6%. Using multivariate analysis, 74.4% of male sinuses and 73.3% of female sinuses were sexed correctly. The overall percentage for sexing maxillary sinuses correctly was 73.9%. It can be concluded that reconstructed CT image can provide valuable measurements for maxillary sinuses and could be used for sexing when other methods of sexing are not conclusive.     

Community-level impacts of temperature on urban street robbery

Purpose

Conduct the first empirical intra-urban examination of community-level connections between street robbery and temperature. Examine whether community socioeconomic status (SES) and crime-relevant land uses strengthen or weaken the temperature impact. A theoretical framework relying on routine activity theory, crime pattern theory, and resident-based control dynamics organized predictions.

Data and methods

For Philadelphia census tracts (n = 381), monthly street robbery counts and temperature data for 36 consecutive months were combined with census and land use data, and analyzed with multilevel models.

Results

Community robbery counts were higher when temperatures were higher, and in lower SES communities. In support of previous work with property crime, but in contrast to previous work with assault, the effects of temperature were stronger in higher SES communities. In support of the integrated model, commercial land use prevalence and subway stations were associated with heightened temperature impacts on robbery.

Conclusions

Community-level fixed and random effects of temperature on urban robbery counts persist when controlling for land use and community structure; further, the random effects depend in part on both. There are implications for understanding indigenous guardianship or informal resident-based place management dynamics, and for planning seasonal police deployments.     

Marked for Death: An Empirical Criminal Careers Analysis of Death Sentences in a Sample of Convicted Male Homicide Offenders

Background

Although prior criminal record and concurrent criminal charges constitute the main eligibility and aggravating circumstances used in capital sentencing, relatively little research has examined the criminal careers of offenders who are ultimately sentenced to death.

Materials and Methods

Using official criminal history data for 618 incarcerated male homicide offenders selected from 8 states—191 of whom were sentenced to death—the current study explored the criminal careers of offenders that received the most severe legal punishment.

Results

Poisson regression incidence rate ratio models indicated that multiple measures of prior criminal activity including contemporaneous and prior history of violence, prior incarceration, early onset of arrest, juvenile homicide offending, and juvenile child molestation were associated with subsequently being sentenced to death. Separate models for white, African American, and Hispanic males showed contrasting effects in their criminal careers and varying relationships between prior criminal career and current capital offending.

Conclusion

The current study adds to the literature on lifespan criminality by applying Poisson regression analyses and a criminal careers approach to study the most extreme offenders including those sentenced to death.