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Applied Statistics Commons™

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2004

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Articles 61 - 71 of 71

Full-Text Articles in Applied Statistics

On Leverage In A Stochastic Volatility Model, Jun Yu Apr 2004

On Leverage In A Stochastic Volatility Model, Jun Yu

Research Collection School Of Economics

This paper is concerned with specification for modelling financial leverage effect in the context of stochastic volatility (SV) models. Two alternative specifications co-exist in the literature. One is the Euler approximation to the well known continuous time SV model with leverage effect and the other is the discrete time SV model of Jacquier, Polson and Rossi (2004, Journal of Econometrics, forthcoming). Using a Gaussian nonlinear state space form with uncorrelated measurement and transition errors, I show that it is easy to interpret the leverage effect in the conventional model whereas it is not clear how to obtain the leverage effect …

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Explaining Death Row's Population And Racial Composition, John H. Blume, Theodore Eisenberg, Martin T. Wells Mar 2004

Explaining Death Row's Population And Racial Composition, John H. Blume, Theodore Eisenberg, Martin T. Wells

Cornell Law Faculty Publications

Twenty-three years of murder and death sentence data show how murder demographics help explain death row populations. Nevada and Oklahoma are the most death-prone states; Texas's death sentence rate is below the national mean. Accounting for the race of murderers establishes that black representation on death row is lower than black representation in the population of murder offenders. This disproportion results from reluctance to seek or impose death in black defendant-black victim cases, which more than offsets eagerness to seek and impose death in black defendant-white victim cases. Death sentence rates in black defendant-white victim cases far exceed those in …

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Attorney Fees In Class Action Settlements: An Empirical Study, Theodore Eisenberg, Geoffrey P. Miller Mar 2004

Attorney Fees In Class Action Settlements: An Empirical Study, Theodore Eisenberg, Geoffrey P. Miller

Cornell Law Faculty Publications

Study of two comprehensive class action case data sets covering 1993-2002 shows that the amount of client recovery is overwhelmingly the most important determinant of the attorney fee award. Even in cases in which the courts engage in the lodestar calculation (the product of reasonable hours and a reasonable hourly rate), the client's recovery generally explains the pattern of awards better than the lodestar. Thus, the time and expense of a lodestar calculation may be wasteful. We also find no robust evidence that either recoveries for plaintiffs or fees of their attorneys increased overtime. The mean fee award in common …

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Ua56/1 Fact Book, Wku Institutional Research Jan 2004

Ua56/1 Fact Book, Wku Institutional Research

WKU Administration Documents

Statistical and demographic profile of WKU.

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Controlling Wound Healing Through Debridement, M. A. Jones, Baojun Song, D. M. Thomas Jan 2004

Controlling Wound Healing Through Debridement, M. A. Jones, Baojun Song, D. M. Thomas

Department of Applied Mathematics and Statistics Faculty Scholarship and Creative Works

The formation of slough (dead tissue) on a wound is widely accepted as an inhibitor to natural wound healing. In this article, a system of differential equations that models slough/wound interaction is developed. We prove a threshold theorem that provides conditions on the amount of slough to guarantee wound healing. As a state-dependent time scale, debridement (the periodic removal of slough) is used as a control. We show that closure of the wound can be reached in infinite time by debriding.

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Uniqueness Theorems In Bioluminescence Tomography, Ge Wang, Yi Li, Ming Jiang Jan 2004

Uniqueness Theorems In Bioluminescence Tomography, Ge Wang, Yi Li, Ming Jiang

Mathematics and Statistics Faculty Publications

Motivated by bioluminescent imaging needs for studies on gene therapy and other applications in the mouse models, a bioluminescence tomography (BLT) system is being developed in the University of Iowa. While the forward imaging model is described by the well-known diffusion equation, the inverse problem is to recover an internal bioluminescent source distribution subject to Cauchy data. Our primary goal in this paper is to establish the solution uniqueness for BLT under practical constraints despite the ill-posedness of the inverse problem in the general case. After a review on the inverse source literature, we demonstrate that in the general case …

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The Dual Spectral Set Conjecture, Steen Pedersen Jan 2004

The Dual Spectral Set Conjecture, Steen Pedersen

Mathematics and Statistics Faculty Publications

Suppose that Λ = (aZ + b) ∪ (cZ + d) where a, b, c, d are real numbers such that a ≠ 0 and c ≠ 0. The union is not assumed to be disjoint. It is shown that the translates Ω + λ, λ is an element of Λ, tile the real line for some bounded measurable set Ω if and only if the exponentials eλ(x) = ei2πλx, λ is an element of Λ, form an orthogonal basis for some bounded measurable set Ω'.

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Reliability Estimation Based On System Data With An Unknown Load Share Rule, Hyoungtae Kim, Paul H. Kvam Jan 2004

Reliability Estimation Based On System Data With An Unknown Load Share Rule, Hyoungtae Kim, Paul H. Kvam

Department of Math & Statistics Faculty Publications

We consider a multicomponent load-sharing system in which the failure rate of a given component depends on the set of working components at any given time. Such systems can arise in software reliability models and in multivariate failure-time models in biostatistics, for example. A load-share rule dictates how stress or load is redistributed to the surviving components after a component fails within the system. In this paper, we assume the load share rule is unknown and derive methods for statistical inference on load-share parameters based on maximum likelihood. Components with (individual) constant failure rates are observed in two environments: (1) …

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A Nonlinear Random Coefficients Model For Degradation Testing, Suk Joo Bae, Paul H. Kvam Jan 2004

A Nonlinear Random Coefficients Model For Degradation Testing, Suk Joo Bae, Paul H. Kvam

Department of Math & Statistics Faculty Publications

As an alternative to traditional life testing, degradation tests can be effective in assessing product reliability when measurements of degradation leading to failure can be observed. This article presents a degradation model for highly reliable light displays, such as plasma display panels and vacuum fluorescent displays (VFDs). Standard degradation models fail to capture the burn-in characteristics of VFDs, when emitted light actually increases up to a certain point in time before it decreases (or degrades) continuously. Random coefficients are used to model this phenomenon in a nonlinear way, which allows for a nonmonotonic degradation path. In many situations, the relative …

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Arbitration And Litigation Of Employment Claims: An Empirical Comparison, Theodore Eisenberg, Elizabeth Hill Jan 2004

Arbitration And Litigation Of Employment Claims: An Empirical Comparison, Theodore Eisenberg, Elizabeth Hill

Cornell Law Faculty Publications

The authors conducted empirical research comparing court case and arbitrated outcomes for employment disputes. In cases not involving civil rights claims, they found little evidence that arbitrated outcomes materially differed from trial outcomes where the claimant was a higher-paid employee. Moreover, they found no statistically significant differences between employee win rates or in the median or mean awards in arbitration and litigation. They also reported evidence indicating that arbitrated disputes conclude more quickly than litigated disputes.

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Deviance Information Criterion For Comparing Stochastic Volatility Models, Andreas Berg, Renate Meyer, Jun Yu Jan 2004

Deviance Information Criterion For Comparing Stochastic Volatility Models, Andreas Berg, Renate Meyer, Jun Yu

Research Collection School Of Economics

Bayesian methods have been efficient in estimating parameters of stochastic volatility models for analyzing financial time series. Recent advances made it possible to fit stochastic volatility models of increasing complexity, including covariates, leverage effects, jump components, and heavy-tailed distributions. However, a formal model comparison via Bayes factors remains difficult. The main objective of this article is to demonstrate that model selection is more easily performed using the deviance information criterion (DIC). It combines a Bayesian measure of fit with a measure of model complexity. We illustrate the performance of DIC in discriminating between various different stochastic volatility models using simulated …

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