4 resultados para MOMENTS

em WestminsterResearch - UK


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In this study, we propose a new semi-nonparametric (SNP) density model for describing the density of portfolio returns. This distribution, which we refer to as the multivariate moments expansion (MME), admits any non-Gaussian (multivariate) distribution as its basis because it is specified directly in terms of the basis density’s moments. To obtain the expansion of the Gaussian density, the MME is a reformulation of the multivariate Gram-Charlier (MGC), but the MME is much simpler and tractable than the MGC when positive transformations are used to produce well-defined densities. As an empirical application, we extend the dynamic conditional equicorrelation (DECO) model to an SNP framework using the MME. The resulting model is parameterized in a feasible manner to admit two-stage consistent estimation and it represents the DECO as well as the salient non-Gaussian features of portfolio return distributions. The in- and out-of-sample performance of a MME-DECO model of a portfolio of 10 assets demonstrate that it can be a useful tool for risk management purposes.

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This paper examines the role of higher-order moments in portfolio choice within an expected-utility framework. We consider two-, three-, four- and five-parameter density functions for portfolio returns and derive exact conditions under which investors would all be optimally plungers rather than diversifiers. Through comparative statics we show the importance of higher-order risk preference properties, such as riskiness, prudence and temperance, in determining plunging behaviour. Empirical estimates for the S&P500 provide evidence for the optimality of diversification.

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This paper addresses affective ‘moments of collusion’ present in feminist research relationships, and contextualises these seemingly personal encounters within a wider systematic framework of the early career researcher and the increasingly neoliberal climate of academia. Focusing on the temporal transition from doctoral research to postdoctorate research positions immediately post-PhD, this paper questions the concept of collusion within (immersive) fieldwork, and examines the delicate and complex question of who is colluding with whom, and for what purpose at different times within the early career academic journey. Specifically, this paper focuses on how the increasing pressures of the neoliberal university play out on our emotions and bodies during fieldwork, an area which still requires attention within the growing critiques of the affects of neo-liberalism in Higher Education. Using personal case studies as springboard for a far wider and important discussion, this paper situates such methodological dilemmas within a broader temporal framework of the increasingly precarious nature of early career academics, where ‘moments of collusion’ may be the only way to keep your head above water.

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US presidents have expanded executive power in times of war and emergency,sometimes aggressively so. This article builds on the application of punctuated equilibria theory by Burnham (1999 and Ackerman (1999). Underpinning this theory is the notion that rapid changes in - or external shocks to - domestic and international society impose new and insistent demands on the state. In so doing, they produce important and decisive moments of institutional mobilization and creativity, disrupt a pre-existing, relatively stable, equilibrium between the Congress and the president, and precipitate decisions or nondecisions by the electorate and political leaders that define the contours for action when the next crisis or external shock occurs. The article suggests that the combination of President George W. Bush's presidentialist doctrine, 9/11 and the 'war' on terror has consolidated a new, constitutional equilibrium. While some members of Congress contest the new order, the Congress collectively has acquiesced in its own marginalization. The article surveys a wide range of executive power assertions and legislative retreats. It argues that power assertions generally draw on precedent: on, for example, a tradition of wartime presidential extraconstitutional leadership extending to presidents, such as John Adams and Abraham Lincoln,as well as to Cold War and post-Cold War presidentialism.