A Deliberative Method for Ranking Risks (II): Evaluation of Validity and Agreement among Risk Managers

A deliberative method for ranking risks was evaluated in a study involving 218 risk managers. Both holistic and multiattribute procedures were used to assess individual and group rankings of health and safety risks facing students at a fictitious middle school. Consistency between the rankings that emerged from these two procedures was reasonably high for individuals and for groups, suggesting that these procedures capture an underlying construct of riskiness. Participants reported high levels of satisfaction with their groups' decision-making processes and the resulting rankings, and these reports were corroborated by regression analyses. Risk rankings were similar across individuals and groups, even though individuals and groups did not always agree on the relative importance of risk attributes. Lower consistency between the risk rankings from the holistic and multiattribute procedures and lower agreement among individuals and groups regarding these rankings were observed for a set of high-variance risks. Nonetheless, the generally high levels of consistency, satisfaction, and agreement suggest that this deliberative method is capable of producing risk rankings that can serve as informative inputs to public risk-management decision making.     

Modelling cell generation times by using the tempered stable distribution

Summary.  We show that the family of tempered stable distributions has considerable potential for modelling cell generation time data. Several real examples illustrate how these distributions can improve on currently assumed models, including the gamma and inverse Gaussian distributions which arise as special cases. Our applications concentrate on the generation times of oligodendrocyte progenitor cells and the yeast Saccharomyces cerevisiae . Numerical inversion of the Laplace transform of the probability density function provides fast and accurate approximations to the tempered stable density, for which no closed form generally exists. We also show how the asymptotic population growth rate is easily calculated under a tempered stable model.     

Explosion Probability of Unexploded Ordnance: Expert Beliefs

This article reports on a study to quantify expert beliefs about the explosion probability of unexploded ordnance (UXO). Some 1,976 sites at closed military bases in the United States are contaminated with UXO and are slated for cleanup, at an estimated cost of $15–140 billion. Because no available technology can guarantee 100% removal of UXO, information about explosion probability is needed to assess the residual risks of civilian reuse of closed military bases and to make decisions about how much to invest in cleanup. This study elicited probability distributions for the chance of UXO explosion from 25 experts in explosive ordnance disposal, all of whom have had field experience in UXO identification and deactivation. The study considered six different scenarios: three different types of UXO handled in two different ways (one involving children and the other involving construction workers). We also asked the experts to rank by sensitivity to explosion 20 different kinds of UXO found at a case study site at Fort Ord, California. We found that the experts do not agree about the probability of UXO explosion, with significant differences among experts in their mean estimates of explosion probabilities and in the amount of uncertainty that they express in their estimates. In three of the six scenarios, the divergence was so great that the average of all the expert probability distributions was statistically indistinguishable from a uniform (0, 1) distribution—suggesting that the sum of expert opinion provides no information at all about the explosion risk. The experts' opinions on the relative sensitivity to explosion of the 20 UXO items also diverged. The average correlation between rankings of any pair of experts was 0.41, which, statistically, is barely significant (p= 0.049) at the 95% confidence level. Thus, one expert's rankings provide little predictive information about another's rankings. The lack of consensus among experts suggests that empirical studies are needed to better understand the explosion risks of UXO.     

A Multistate Life Table Analysis of Union Regimes in the United States: Trends and Racial Differentials, 1970–2002

We estimate trends and racial differentials in marriage, cohabitation, union formation and dissolution (union regimes) for the period 1970–2002 in the United States. These estimates are based on an innovative application of multistate life table analysis to pooled survey data. Our analysis demonstrates (1) a dramatic increase in the lifetime proportions of transitions from never-married, divorced or widowed to cohabiting; (2) a substantial decrease in the stability of cohabiting unions; (3) a dramatic increase in mean ages at cohabiting after divorce and widowhood; (4) a substantial decrease in direct transition from never-married to married; (5) a significant decrease in the overall lifetime proportion of ever marrying and re-marrying in the 1970s to 1980s but a relatively stable pattern in the 1990s to 2000–2002; and (6) a substantial decrease in the lifetime proportion of transition from cohabiting to marriage. We also present, for the first time, comparable evidence on differentials in union regimes between four racial groups.     

Transnational communities and business systems

The paper examines the concept of ‘transnational communities’ as a way of understanding globalization practices in business and management. It argues that ‘transnational communities’ are emergent properties of the internationalizing of economic activity. Three specific aspects of this process are considered in detail: the development of multinational companies; the development of international regulatory bodies; and the development of cognitive and normative frameworks through the practices of business education, management consultancies and other global professional service firms. It is argued that in each case, transnational spaces are emerging; within these spaces, transnational communities are developing. The article calls for more research into the diverse nature of these spaces and communities as a way of avoiding the sterile polarities of what Held et al. (1999) refer to as the ‘hyperglobalists’ and the ‘sceptics’.     

Individual perceptions and the social construction of hate crimes: A factorial survey

Although the rapid diffusion of hate crime legislation since the 1980s indicates widespread success of the antiviolence movement at the policy level, effective responses to hate crimes – such as reporting incidents to authorities – are partly contingent on how individuals initially interpret potential incidents. This paper investigates the degree to which individuals’ perceptions of concrete events of harassment and violence mirror the interpretive frameworks offered by proponents of hate crime legislation. Specifically, the study examines the determinants of definitions of hate crime and perceptions of seriousness, focusing on both incident-level and respondent-level variables. Using data from a multilevel factorial survey gathered from a sample of undergraduates, I find a general alignment between the political construction of hate crimes and college student perceptions of incidents of harassment and violence, although sensitivity to hate crimes varies by witness demographic and attitudinal characteristic.     

Insurance decisions for low-probability losses

It is widely accepted that individuals tend to underinsure against low-probability, high-loss events relative to high-probability, low-loss events. This conventional wisdom is based largely on field studies, as there is very little experimental evidence. We reexamine this issue with an experiment that accounts for possible confounds in prior insurance experiments. Our results are counter to the prior experimental evidence, as we observe subjects buying more insurance for lower-probability events than for higher-probability events, given a constant expected loss and load factor. Insofar as underinsurance for catastrophic risk is observed in the field, our results suggest that this can be attributed to factors other than only the relative probability of the loss events.

Methodologic challenges of e-health research

In this article, research-based strategies used in a web-based study to assess the impact of participation in cancer-related mailing lists on cancer survivors and caregivers are highlighted. The paper presents alternative methods of measuring response rates in Internet surveys. Response rate estimation, based on American Association for Public Opinion Research guidelines, ranged between 15% and 24.9% for the study. Several strategies were implemented to increase survey participation and reduce item nonresponse. Few participants opted for a telephone survey as an alternative to a web-administered design (mixed-mode administration). Using time-stamp data to diagnose places in the questionnaire where respondents prematurely exited or broke off survey participation, we were able to decrease premature break offs. A lottery was also implemented to increase response rates. The experience of obtaining institutional review board approval for the lottery is also described. Preliminary data indicate slight increases in response rates subsequent to implementing the lottery.     

Domestic violence in veterans with posttraumatic stress disorder who seek couples therapy

Domestic violence rates among veterans with posttraumatic stress disorder (PTSD) are higher than those of the general population. Individuals who have been diagnosed with PTSD who seek couples therapy with their partners constitute an understudied population. Self-report measures of domestic violence, relationship satisfaction, and intimacy were administered at intake to 179 couples seeking relationship therapy at a Veterans Affairs clinic. Couples in which the veteran was diagnosed with combat-related PTSD were compared with two other groups based on the veteran's primary diagnosis (depression, adjustment disorder/V-code). Both the PTSD- and depression-diagnosed veterans perpetrated more violence than did those with adjustment/V-code diagnoses. Domestic violence rates among depressed and PTSD-diagnosed veterans were much higher than those found in previous research. Implications for assessment and treatment are discussed.