Consequences and Costs of Closing a Publicly Funded Methadone Maintenance Clinic

Objective. We examine volunteering to support the relief effort after the bombing of the Murrah Federal Building. We address two issues: (1) how widespread was volunteering and what forms did it take, and (2) does Wilson and Musick’s (1997a) “integrated theory of volunteer work” help to explain variation in volunteering in this disaster situation? Methods. We use data from the 1996 Oklahoma City Survey (OKC Survey). The 1996 OKC Survey is based on a random sample of the adult population of Oklahoma City and was administered 10 months after the bombing. Results. Nearly 75 percent of the sample respondents volunteered to support the relief effort in at least one way; giving money and donating nonprofessional goods or services were the two most prevalent volunteer activities. Socioeconomic status, knowing someone killed or injured in the bombing, belonging to voluntary organizations before the bombing, and being affiliated with a religious denomination were predictors of volunteering, depending on the type of volunteer activity considered. Conclusions. The magnitude of volunteering after the Murrah Building bombing was in line with volunteer efforts after other disasters. The integrated theory of volunteer work is a useful framework for studying volunteering after disasters.     

High Stakes and Acceptance Behavior in Ultimatum Bargaining:

This paper presents the results of a within-subject experiment testing whether an increase in the monetary stakes by a factor of 50 – which had never been done before – influences individual behavior in a simple ultimatum bargaining game. Contrary to current wisdom, we found that lowest acceptable offers stated by the responder are proportionally lower in the high-stake condition than in the low-stake condition. This result may be interpreted in terms of the type of utility functions which characterize the subjects. However, in line with prior results, we find that an important increase of the monetary stakes in the ultimatum game has no effect on the offers made by the proposer. Yet, the present research suggests that the reasons underlying these offers are quite different when the stakes are high.     

On robust forecasting in dynamic vector time series models

In this article, robust estimation and prediction in multivariate autoregressive models with exogenous variables (VARX) are considered. The conditional least squares (CLS) estimators are known to be non-robust when outliers occur. To obtain robust estimators, the method introduced in Duchesne [2005. Robust and powerful serial correlation tests with new robust estimates in ARX models. J. Time Ser. Anal. 26, 49–81] and Bou Hamad and Duchesne [2005. On robust diagnostics at individual lags using RA-ARX estimators. In: Duchesne, P., Rémillard, B. (Eds.), Statistical Modeling and Analysis for Complex Data Problems. Springer, New York] is generalized for VARX models. The asymptotic distribution of the new estimators is studied and from this is obtained in particular the asymptotic covariance matrix of the robust estimators. Classical conditional prediction intervals normally rely on estimators such as the usual non-robust CLS estimators. In the presence of outliers, such as additive outliers, these classical predictions can be severely biased. More generally, the occurrence of outliers may invalidate the usual conditional prediction intervals. Consequently, the new robust methodology is used to develop robust conditional prediction intervals which take into account parameter estimation uncertainty. In a simulation study, we investigate the finite sample properties of the robust prediction intervals under several scenarios for the occurrence of the outliers, and the new intervals are compared to non-robust intervals based on classical CLS estimators.     

Family size and optimal income taxation

This paper studies the role of family size in the design of optimal income taxation. We consider a second best setting where the government observes the number of children and the income of the parents but not their productivity. With a linear tax schedule the marginal tax rate is shown to decrease with the number of children, while the relationship between the demogrant and family size appears to be ambiguous. With two ability levels, optimal non-linear income tax implies zero marginal tax rates for the higher ability parents; low ability parents have positive marginal tax rates that decrease with family size. Received: 4 September 2000/Accepted: 17 May 2001     

Uncertainty and Sensitivity Analysis in Assessment of the Thyroid Cancer Risk Related to Chernobyl Fallout in Eastern France

The increase in the thyroid cancer incidence in France observed over the last 20 years has raised public concern about its association with the 1986 nuclear power plant accident at Chernobyl. At the request of French authorities, a first study sought to quantify the possible risk of thyroid cancer associated with the Chernobyl fallout in France. This study suffered from two limitations. The first involved the lack of knowledge of spontaneous thyroid cancer incidence rates (in the absence of exposure), which was especially necessary to take their trends into account for projections over time; the second was the failure to consider the uncertainties. The aim of this article is to enhance the initial thyroid cancer risk assessment for the period 1991-2007 in the area of France most exposed to the fallout (i.e., eastern France) and thereby mitigate these limitations. We consider the changes over time in the incidence of spontaneous thyroid cancer and conduct both uncertainty and sensitivity analyses. The number of spontaneous thyroid cancers was estimated from French cancer registries on the basis of two scenarios: one with a constant incidence, the other using the trend observed. Thyroid doses were estimated from all available data about contamination in France from Chernobyl fallout. Results from a 1995 pooled analysis published by Ron et al. were used to determine the dose-response relation. Depending on the scenario, the number of spontaneous thyroid cancer cases ranges from 894 (90% CI: 869-920) to 1,716 (90% CI: 1,691-1,741). The number of excess thyroid cancer cases predicted ranges from 5 (90% UI: 1-15) to 63 (90% UI: 12-180). All of the assumptions underlying the thyroid cancer risk assessment are discussed.     

Ratio-Scale Measurement with Intransitivity or Incompleteness: The Homogeneous Case

In the homogeneous case of one-dimensional objects, we show that any relation that is positive and homothetic can be represented by a ratio-scale and a unique and constant biasing factor. This factor may favor or disfavor the preference for an object over another. In the first case, preferences are complete but not transitive and an object may be preferred even when its value is lower. In the second case, preferences are asymmetric and transitive but not negatively transitive and it may not be sufficient for an object to have a greater value to be preferred. In this manner, the biasing factor reflects the extent to which preferences may depart from a maximization process.