Maximum likelihood estimation of Laplace parameters based on general type-II censored examples

In this paper, we derive the maximum likelihood estimators of the parameters of a Laplace distribution based on general Type-II censored samples. The resulting explicit MLE's turn out to be simple linear functions of the order statistics. We then examine the asymptotic variance of the estimates by calculating the elements of the Fisher information matrix.     

Reinforcement,stereotypy, and rule discovery

The effects of reinforced pretraining on subsequent rule discovery were examined with college students as subjects. Levels of behavioral stereotypy observed during reinforced and non-contingent pretraining were compared. During pretraining subjects received reinforcement if they pressed two keys in a particular sequence. During the problem session pressing each key four times was a necessary condition for reinforcement, but each problem had additional different requirements for reinforcement. Subjects were asked to solve the problems by discovering the rule that determined whether or not they received reinforcement. Levels of stereotyped responding during pretraining were equivalent for contingently and non-contingently trained subjects. During the problem session contingently pretrained, non-contingently pretrained, and naive subjects required equal numbers of trials to solve problems and solved the same number of problems. The results suggest that behavioral stereotypy observed in this experimental preparation may be due to repeated exposure to the task. Differences between the results observed in this study and that of Schwartz (1982) and implications for the use of reinforcement procedures in applied settings are discussed.

     

Higher order moments of order statistics from INID symmetric random variables

In this paper we present analogues of Balakrishnan's (1989) relations that relate the triple and quadruple moments of order statistics from independent and nonidentically distributed (I.NI.D.) random variables from a symmetric distribution to those of the folded distribution. We then apply these results, along with the corresponding recurrence relations for the exponential distribution derived recently by Childs (2003), to study the robustness of the Winsorized variance.     

The cult of Champ Man: the culture and pleasures of Championship Manager/Football Manager gamers

This paper considers the popularity and social significance of the gaming series Championship Manager/Football Manager. Sport-related games continue to be one of the most popular forms of digital gaming, and the series has proved to be one of the most successful of all time. Drawing on 32 interviews with game players and developers of this series, this paper argues that this series has proved particularly popular due to its 'intertextual' links to the sport of football, which allows this game to be drawn on as a resource in conversations and social networks. In particular, this paper argues that aspects of gaming, such as performativity and control, extend and cross-cut with wider social formations. Hence, the author argues that it is crucial that considerations of digital games seek to locate these within wider social and cultural patterns.     

Characterizing Environmental Harm: Developments in an Approach to Strategic Risk Assessment and Risk Management

Environmental policymakers and regulators are often in the position of having to prioritize their actions across a diverse range of environmental pressures to secure environmental protection and improvements. Information on environmental issues to inform this type of strategic analysis can be disparate; it may be too voluminous or even absent. Data on a range of issues are rarely presented in a common format that allows easy analysis and comparison. Nevertheless, judgments are required on the significance of various environmental pressures and on the inherent uncertainties to inform strategic assessments such as “state of the environment” reports. How can decisionmakers go about this type of strategic and comparative risk analysis? In an attempt to provide practical tools for the analysis of environmental risks at a strategic level, the Environment Agency of England and Wales has conducted a program of developmental research on strategic risk assessment since 1996. The tools developed under this program use the concept of “environmental harm” as a common metric, viewed from technical, social, and economic perspectives, to analyze impacts from a range of environmental pressures. Critical to an informed debate on the relative importance of these perspectives is an understanding and analysis of the various characteristics of harm (spatial and temporal extent, reversibility, latency, etc.) and of the social response to actual or potential environmental harm from a range of hazards. Recent developments in our approach, described herein, allow a presentation of the analysis in a structured fashion so as to better inform risk‐management decisions.     

An analysis of two probabilistic model induction techniques

Two probabilistic model induction techniques, cart and constructor, are compared, via a series of experiments, in terms of their ability to induce models that are both interpretable and predictive. The experiments show that, although both algorithms are able to deliver classifiers with predictive performance close to that of the optimal Bayes rule,constructor is able to generate a probabilistic model that is more easily interpretable than the cart model. On the other hand, cart is a more mature algorithm and is capable of handling many more situations (e.g., real-valued training sets) thanconstructor. A variety of characteristics of both algorithms are compared, and suggestions for future research are made.     

A changed America? The effects of September 11th on depressive symptoms and alcohol consumption

In the weeks following the terrorist attacks of September 11, 2001, social commentators argued that America had profoundly "changed." In light of these arguments and the literature on disasters, we examine the immediate and longer-term mental health consequences of September 11th using a national sample of full-time American workers. We model the effects of temporal proximity to the attacks on depressive symptoms and alcohol consumption, while controlling for demographic characteristics. Our data revealed a significant increase in the number of depressive symptoms reported during the 4 weeks after the attacks. In the subsequent weeks, levels of depressive symptoms returned to pre-September 11th levels. Contrary to expectations, there was some indication of decreased alcohol consumption after September 11th, although these effects were modest. These analyses provide little support for popular assertions that September 11th resulted in lasting and measurable impacts on Americans' well-being.