A note on portraying the accuracy of violence predictions

We discuss two major reviews of the accuracy of dichotomous (yes/no) violence predictions (Monahan, 1981; Otto, 1992), which reported rates offalse positive errors that were calculated using conceptually and mathematically dissimilar methods. We outline potential problems that result from analyzing data in the form of 2×2 contingency tables and offer some recommendations for future research on the prediction of violence.     

Complex Causal Relations and Case Study Methods: The Example of Path Dependence

Colin Elman Department of Political Science, Arizona State University, Box 873902, Tempe, AZ 85287-3902 e-mail: bennetta{at}georgetown.edu e-mail: colin.elman{at}asu.edu (corresponding author) This article discusses the application of qualitative methodsin analyzing causal complexity. In particular, the essay reviewshow process tracing and systematic case comparisons can addresspath-dependent explanations. The article unpacks the conceptof path dependence and its component elements of causal possibility,contingency, closure of alternatives, and constraints to thecurrent path. The article then reviews four strengths that casestudies bring to the study of path dependence: offering a detailedand holistic analysis of sequences in historical cases, beingsuitable for the study of rare events, facilitating the searchfor omitted variables that might lie behind contingent events,and allowing for the study of interaction effects within oneor a few cases.     

Canada's Assisted Human Reproductive Act: is it scientific censorship, or a reasoned approach to the regulation of rapidly emerging reproductive technologies?

After more than a decade of study, discussion and debate, the Canadian House of Commons and Senate have approved the Assisted Human Reproduction Act. Building on the earlier Bill C-47, which died on the order paper in 1997, the Act bans human cloning for reproductive or therapeutic purposes, payment for surrogacy arrangements, and trading in human reproductive materials or their use without informed consent. In addition, the Act significantly restricts research using human reproductive materials. This article compares the Act to legislative regimes in other nations with advanced human reproductive science. It concludes that while the Act has many laudable goals, it is flawed in that it tries to cover too much legislative ground. As a result it unreasonable impairs the ability of Canadian scientists to compete in areas such as stem cell research, and area that is expected to yield significant new approaches to treating human disease.     

How the probability of a false positive affects the value of DNA evidence

Errors in sample handling or test interpretation may cause false positives in forensic DNA testing. This article uses a Bayesian model to show how the potential for a false positive affects the evidentiary value of DNA evidence and the sufficiency of DNA evidence to meet traditional legal standards for conviction. The Bayesian analysis is contrasted with the "false positive fallacy," an intuitively appealing but erroneous alternative interpretation. The findings show the importance of having accurate information about both the random match probability and the false positive probability when evaluating DNA evidence. It is argued that ignoring or underestimating the potential for a false positive can lead to serious errors of interpretation, particularly when the suspect is identified through a "DNA dragnet" or database search, and that ignorance of the true rate of error creates an important element of uncertainty about the value of DNA evidence.     

A Comparative Study of Children and Adult Homicide Rates in the USA and the Major Western Countries 1974–1999: Grounds for Concern?

The aim of this study is to examine the changing patterns of child homicide in the USA and the other 9 major Western countries between 1974 and 1999. On the basis of standardized WHO mortality data, 5-year mean rates of Baby (<1 year), Infant (1–4), Child (5–14), and General Population Rates for Homicide (GPRH) were analyzed for 1974–78 and 1995–99 for the USA and major Western countries. The analysis provided ratios of change for children's homicide between 1974 and 1999 and ratio of ratios between adult' and children's homicide. Over the period USA male Baby homicide rose by 78% and Females 44% with a combined rise in All Children [0–14] homicides of 45%, within the context of a declining adult GPRH. In the 1970s, 3 major Western countries had either higher or similar children's homicide rates to the USA, but by the late 1990s none did. Moreover, between 1974 and 1999, the USA had the biggest rise in Baby (<1) and All Children's deaths, and only France had substantial increases, whereas Baby homicide rates fell significantly in 6 other countries. The findings indicate a worrying deterioration in U.S. child homicides. Possible links with child abuse and explanations for the results are briefly discussed. Urgent case-specific research is required to determine the cause/s for and how to reverse the worsening child homicide situation in the USA.     

Autopsy artifact created by the Revivant AutoPulse resuscitation device

In certain cases, the evaluation and correct identification of resuscitative artifacts is critical to the correct diagnosis and determination of the cause and manner of death. Resuscitative artifacts can resemble homicidal or accidental injury and thus possibly be misinterpreted. Occasionally, new technologies and/or medical procedures will create original and/or distinctive artifacts. In 2003, the San Francisco Fire Department emergency personnel began field-testing the Revivant AutoPulse, an automated chest compression device. This device is currently being used in two other counties in the San Francisco Bay Area as well as regions of Florida, Virginia, and Ohio. We present three cases of resuscitative artifact that could be potentially confused with homicidal or accidental injury. These cases illustrate resuscitative artifacts, specifically lateral chest and horizontally oriented upper abdomen cutaneous abrasions created by this automated chest compression device.