A Bayesian approach for improved pavement performance prediction

We present a method for predicting future pavement distresses such as longitudinal cracking. These predicted distress values are used to plan road repairs. Large inherent variability in measured cracking and an extremely small number of observations are the nature of the pavement cracking data, which calls for a parametric Bayesian approach. We model theoretical pavement distress with a sigmoidal equation with coefficients based on prior engineering knowledge. We show that a Bayesian formulation akin to Kalman filtering gives sensible predictions and provides defendable uncertainty statements for predictions. The method is demonstrated on data collected by the Texas Transportation Institute at several sites in Texas. The predictions behave in a reasonable and statistically valid manner.     

Efficiency of Betting Markets and Rationality of Players: Evidence from the French 6/49 Lotto

We analyse the existence of preferred numbers on the French Lotto market and prove that this market is not strongly efficient in the sense of Thaler & Ziemba (1988). The preference for low numbers is investigated by means of stochastic dominance tests. The specific features of the French Lotto game allow us to build a simple estimate of the probability distribution of numbers actually played. The results are compared with the (highly time-consuming) maximum likelihood estimator used by Farrell et al. (2000). It is shown that the two methods give very close results. Our conclusions stress the perspectives of this study in various domains.     

Mother–Infant Person‐ and Object‐Directed Interactions in Latino Immigrant Families: A Comparative Approach

Cultural variation in durations, relations, and contingencies of mother–infant person‐and object‐directed behaviors were examined for 121 nonmigrant Latino mother–infant dyads in South America, Latina immigrants from South America and their infants living in the United States, and European American mother–infant dyads. Nonmigrant Latina mothers and infants engaged in person‐directed behaviors longer than Latino immigrant or European American mothers and infants. Mother and infant person‐directed behaviors were positively related; mother and infant object‐related behaviors were related for some cultural groups but not others. Nearly all mother and infant behaviors were mutually contingent. Mothers were more responsive to infants' behaviors than infants were to mothers. Some cultural differences in responsiveness emerged. Immigrant status has a differentiated role in mother–infant interactions.     

Regulating Under Uncertainty: Newsboy for Exposure Limits

Setting action levels or limits for health protection is complicated by uncertainty in the dose-response relation across a range of hazards and exposures. To address this issue, we consider the classic newsboy problem. The principles used to manage uncertainty for that case are applied to two stylized exposure examples, one for high dose and high dose rate radiation and the other for ammonia. Both incorporate expert judgment on uncertainty quantification in the dose-response relationship. The mathematical technique of probabilistic inversion also plays a key role. We propose a coupled approach, whereby scientists quantify the dose-response uncertainty using techniques such as structured expert judgment with performance weights and probabilistic inversion, and stakeholders quantify associated loss rates.     

China Regional Income Convergence:Using Spatial Panel data

This paper uses spatial panel data models to analyze regional growth in China.Controlling for fixed-effects allows us to disentangle the effect of spatial dependence from that of spatial heterogeneity and omitted variable to investigate the regional convergence process within the country.     

Missing data: Discussion points from the PSI missing data expert group

The Points to Consider Document on Missing Data was adopted by the Committee of Health and Medicinal Products (CHMP) in December 2001. In September 2007 the CHMP issued a recommendation to review the document, with particular emphasis on summarizing and critically appraising the pattern of drop‐outs, explaining the role and limitations of the ‘last observation carried forward’ method and describing the CHMP's cautionary stance on the use of mixed models. In preparation for the release of the updated guidance document, statisticians in the Pharmaceutical Industry held a one‐day expert group meeting in September 2008. Topics that were debated included minimizing the extent of missing data and understanding the missing data mechanism, defining the principles for handling missing data and understanding the assumptions underlying different analysis methods. A clear message from the meeting was that at present, biostatisticians tend only to react to missing data. Limited pro‐active planning is undertaken when designing clinical trials. Missing data mechanisms for a trial need to be considered during the planning phase and the impact on the objectives assessed. Another area for improvement is in the understanding of the pattern of missing data observed during a trial and thus the missing data mechanism via the plotting of data; for example, use of Kaplan–Meier curves looking at time to withdrawal. Copyright © 2009 John Wiley & Sons, Ltd.     

Introduction to the Special Issue on Theory Development in Operations Management

Rigorous development of theory in operations management has been lacking. Although many theories have been proposed, they are often not developed in a format and depth that can be falsified, refined, or supported. This special issue includes three papers that illustrate rigorous development of theory for future testing using mathematical, simulation, or managerial approaches.