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Selected AbstractsTesting Parameters in GMM Without Assuming that They Are IdentifiedECONOMETRICA, Issue 4 2005Frank Kleibergen We propose a generalized method of moments (GMM) Lagrange multiplier statistic, i.e., the K statistic, that uses a Jacobian estimator based on the continuous updating estimator that is asymptotically uncorrelated with the sample average of the moments. Its asymptotic ,2 distribution therefore holds under a wider set of circumstances, like weak instruments, than the standard full rank case for the expected Jacobian under which the asymptotic ,2 distributions of the traditional statistics are valid. The behavior of the K statistic can be spurious around inflection points and maxima of the objective function. This inadequacy is overcome by combining the K statistic with a statistic that tests the validity of the moment equations and by an extension of Moreira's (2003) conditional likelihood ratio statistic toward GMM. We conduct a power comparison to test for the risk aversion parameter in a stochastic discount factor model and construct its confidence set for observed consumption growth and asset return series. [source] Missing links: Eugène Dubois and the origins of paleoanthropologyEVOLUTIONARY ANTHROPOLOGY, Issue 3 2002Pat Shipman Abstract Examining the origins of various scientific fields may help to identify particular individuals whose thought, work, and discoveries have had a disproportionately large influence. Such individuals seem to serve as catalysts for a wider set of intellectual reactions, which then give rise to an entire field of study. In this paper, we propose explicit criteria for recognizing the founders of new fields. We contend that Eugène Dubois, best known as the man who found the "missing link" between apes and humans, should be recognized as one of the founding fathers of paleoanthropology. [source] SOCIAL CONSTRUCTION OF HYDROPOLITICS: THE GEOGRAPHICAL SCALES OF WATER AND SECURITY IN THE INDUS BASIN,GEOGRAPHICAL REVIEW, Issue 4 2007Daanish Mustafa ABSTRACT. The article identifies important themes and future research directions for analyzing water and conflict dynamics at the subnational scale in the Indus Basin. A historical overview of water development in the Indus Basin suggests that the water-security nexus was always a salient theme in the minds of water developers, even in the nineteenth century. Conflicts over contemporary large-scale water-development projects in the Indian and Pakistani parts of the Indus Basin are reviewed. Engineers' single-minded focus on megaprojects, to the neglect of the wider set of values that societies attach to water resources in the eastern and western Indus Basin are largely to blame for continuing low-grade conflict in the basin. A review of local-level conflicts over water supply and sanitation in Karachi and the distribution of irrigation water in Pakistani Punjab illustrates the critical role of governance and differential social power relations in accentuating conflict. The article argues against neo-Malthusian assumptions about the inevitability of conflict over water because of its future absolute scarcity. Instead, the article seeks to demonstrate that, despite evidence suggesting that international armed conflict over water does not exist, the potential for political instability over domestic water distribution and development issues is real. The question of whether conflict at the subnational scale will culminate in violence will depend on how water-resources institutions in the basin behave. [source] Obtaining smooth mesh transitions using vertex optimization,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2008M. Brewer Abstract Mesh optimization has proven to be an effective way to improve mesh quality for arbitrary Lagrangian Eulerian (ALE) simulations. To date, however, most of the focus has been on improving the geometric shape of individual elements, and these methods often do not result in smooth transitions in element size or aspect ratio across groups of elements. We present an extension to the mean ratio optimization that addresses this problem and yields smooth transitions within regions and across regions in the ALE simulation. While this method is presented in the context of ALE simulations, it is applicable to a wider set of applications that require mesh improvement, including the mesh generation process. Published in 2007 by John Wiley & Sons, Ltd. [source] Bayesian estimation of traffic lane stateINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2003Ivan Nagy Abstract Modelling of large transportation systems requires a reliable description of its elements that can be easily adapted to the specific situation. This paper offers mixture model as a flexible candidate for modelling of such element. The mixture model describes particular and possibly very different states of a specific system by its individual components. A hierarchical model built on such elements can describe complexes of big city communications as well as railway or highway networks. Bayesian paradigm is adopted for estimation of parameters and the actual component label of the mixture model as it serves well for the subsequent decision making. As a straightforward application of Bayesian method to mixture models leads to infeasible computations, an approximation is applied. For normal stochastic variations, the resulting estimation algorithm reduces to a simple recursive weighted least squares. The elementary modelling is demonstrated on a model of traffic flow state in a single point of a roadway. The examples for simulated as well as real data show excellent properties of the suggested model. They represent much wider set of extensive tests made. Copyright © 2003 John Wiley & Sons, Ltd. [source] Disruption-management strategies for short life-cycle productsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 4 2009Brian Tomlin Abstract Supplier diversification, contingent sourcing, and demand switching (whereby a firm shifts customers to a different product if their preferred product is unavailable), are key building blocks of a disruption-management strategy for firms that sell multiple products over a single season. In this article, we evaluate 12 possible disruption-management strategies (combinations of the basic building-block tactics) in the context of a two-product newsvendor. We investigate the influence of nine attributes of the firm, its supplier(s), and its products on the firs preference for the various strategies. These attributes include supplier reliability, supplier failure correlation, payment responsibility in the event of a supply failure, product contribution margin, product substitutability, demand uncertainties and correlation, and the decision makes risk aversion. Our results show that contingent sourcing is preferred to supplier diversification as the supply risk (failure probability) increases, but diversification is preferred to contingent sourcing as the demand risk (demand uncertainty) increases. We find that demand switching is not effective at managing supply risk if the products are sourced from the same set of suppliers. Demand switching is effective at managing demand risk and so can be preferred to the other tactics if supply risk is low. Risk aversion makes contingent sourcing preferable over a wider set of supply and demand-risk combinations. We also find a two-tactic strategy provides almost the same benefit as a three-tactic strategy for most reasonable supply and demand-risk combinations. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009 [source] The Limits of Rational Choice: New Institutionalism in the Test Bed of Central Banking Politics in AustraliaPOLITICAL STUDIES, Issue 3 2002Stephen Bell This paper tests the explanatory capacities of different versions of new institutionalism by examining the Australian case of a general transition in central banking practice and monetary politics: namely, the increased emphasis on low inflation and central bank independence. Standard versions of rational choice institutionalism largely dominate the literature on the politics of central banking, but this approach (here termed RC1) fails to account for Australian empirics. RC1 has a tendency to establish actor preferences exogenously to the analysis; actors'motives are also assumed a priori; actor's preferences are depicted in relatively static, ahistorical terms. And there is the tendency, even a methodological requirement, to assume relatively simple motives and preference sets among actors, in part because of the game theoretic nature of RC1 reasoning. It is possible to build a more accurate rational choice model by re-specifying and essentially updating the context, incentives and choice sets that have driven rational choice in this case. Enter RC2. However, this move subtly introduces methodological shifts and new theoretical challenges. By contrast, historical institutionalism uses an inductive methodology. Compared with deduction, it is arguably better able to deal with complexity and nuance. It also utilises a dynamic, historical approach, and specifies (dynamically) endogenous preference formation by interpretive actors. Historical institutionalism is also able to more easily incorporate a wider set of key explanatory variables and incorporate wider social aggregates. Hence, it is argued that historical institutionalism is the preferred explanatory theory and methodology in this case. [source] Are Women at Greater Risk?THE AMERICAN JOURNAL ON ADDICTIONS, Issue 3 2009An Examination of Alcohol-Related Consequences, Gender Men typically drink more than women; however, women achieve higher BACs (blood alcohol concentration) than men at equivalent consumption levels. This study investigated the unique effect of gender on individual alcohol problems by controlling both consumption and intoxication in a sample of 1,331 undergraduate drinkers. Gender independently influenced the risk of experiencing seven of nine negative consequences: (a) being female increased risk for tolerance, blacking out, passing out, drinking after promising not to, and getting injured; (b) being male increased risk for damaging property and going to school drunk. Gender patterns should be explored in a wider set of alcohol-related problems. [source] Changing Public Service Organizations: Current Perspectives and Future ProspectsBRITISH JOURNAL OF MANAGEMENT, Issue 2003Ewan Ferlie As governments and public service organizations across the globe engage in strategies of institutional and organizational change, it is timely to examine current developments and a future research agenda for public governance and management. The paper commences with reflections on the state of the field, based on an analysis of papers published in the British Journal of Management over the last decade. While there was some variation apparent across the set, the ,typical' article was found to be influenced by the discipline of organizational behaviour, set within the health-care sector, using case-study methods within field-based studies, and investigating shifts in roles and relationships and the management of change. It has also in the past been UK-centric, though the journal editorial policy and our own article call for a stronger international and comparative focus in the future. The second section of the article summarizes the articles and themes contained in this collection of papers on public service organizations. The third section explores a possible research agenda for the future, arguing for the significance of public sector research for the understanding of management more generally, and for examining the interface between private and public organizations (an increasingly common phenomenon). We suggest the need to set public services research in policy and political contexts, and suggest this may reveal organizational processes of wide interest. We call for a wider set of disciplines to engage in public management research, and to engage in moving the agenda from the study of efficiency to effectiveness as defined by a variety of stakeholders. We address the issue of how far public management researchers should become directly engaged with the world of policy and suggest that whether researchers engage in Mode 1 or Mode 2 research, their work would benefit from a stronger theoretical base. [source] | ||||||||||||||||