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Search Results: 1 - 10 of 32341 matches for " Peter McElroy "
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Estimation of Causal Invertible VARMA Models
Anindya Roy,Tucker S. McElroy,Peter Linton
Statistics , 2014,
Abstract: We present a re-parameterization of vector autoregressive moving average (VARMA) models that allows estimation of parameters under the constraints of causality and invertibility. The parameter constraints associated with a causal invertible VARMA model are highly complex. Currently there are no procedures that can maintain the constraints in the estimated VARMA process, except in the special case of a vector autoregression (VAR), where some moment based causal estimators are available. Even in the VAR case, the available likelihood based estimators are not causal. The maximum likelihood estimator based on the full likelihood that does not condition on the initial observations by definition satisfies the causal invertible constraints but optimization of the likelihood under the complex constraints is an intractable problem. The commonly used Bayesian procedure for VAR often has posterior mass outside the causal set because the priors are not constrained to the causal set of parameters. We provide an exact mathematical solution to this problem. An $m$-variate VARMA$(p, q)$ process contains $(p+ q) m^2 + \binom{m+1}{2}$ parameters, which must be constrained to a subset of Euclidean space in order to guarantee causality and invertibility. This space is implicitly described in this paper, through the device of parameterizing the entire space of block Toeplitz matrices in terms of positive definite matrices and orthogonal matrices. The parameterization has connection to Schur- stability of polynomials and the associated Stein transformation that are often used in dynamical systems literature. As an important by-product of our investigation, we generalize a classical result in dynamical systems to provide a characterization of Schur stable matrix polynomials.
Contra Copyright, Again
Wendy McElroy
Libertarian Papers , 2011,
Abstract: This revised version of the author’s 1985 article “Contra Copyright” includes a new, introductory section explaining the background of the author’s path to copyright abolitionism. The main article surveys various libertarian debates on this issue, including the anti-intellectual property (IP) views of Benjamin Tucker and the pro-IP views of Lysander Spooner. McElroy argues that the issue of copyright hinges on the question: can ideas be property? Because only scarce goods can be property, and ideas are not scarce, copyright must be rejected as unjustified.
Book Review: Martin Kahl (Ed.). The Transnationalisation of Risks of Violence. Baden-Baden: Nomos Verlagsgesellschaft. 2011.
Erin McElroy
Journal of International and Global Studies , 2012,
Incompatibility of trends in multi-year estimates from the American Community Survey
Tucker McElroy
Statistics , 2010, DOI: 10.1214/09-AOAS259
Abstract: The American Community Survey (ACS) provides one-year (1y), three-year (3y) and five-year (5y) multi-year estimates (MYEs) of various demographic and economic variables for each "community", although the 1y and 3y may not be available for communities with a small population. These survey estimates are not truly measuring the same quantities, since they each cover different time spans. Using some simplistic models, we demonstrate that comparing different period-length MYEs results in spurious conclusions about trend movements. A simple method utilizing weighted averages is presented that reduces the bias inherent in comparing trends of different MYEs. These weighted averages are nonparametric, require only a short span of data, and are designed to preserve polynomial characteristics of the time series that are relevant for trends. The basic method, which only requires polynomial algebra, is outlined and applied to ACS data. In some cases there is an improvement to comparability, although a final verdict must await additional ACS data. We draw the conclusion that MYE data is not comparable across different periods.
生物技术通报 , 1996,
Abstract: <正>最近由于转化技术的长足进步,已在越来越多的禾谷类作物中培育出转基因植株。为了借助基因工程改良禾谷类作物的品质及其它农艺性状,目前的重点已开始放在那些能调控外源基因在转基因禾谷类作物中表达的分子元件的鉴定上。禾谷类作物包括一大群具有经济价值的植物种,如果引入一些控制优良品质及其它农艺性状如抗病性和抗逆性的外源基因,并让其表达,那么这些作物对人类的价值会更高。然而,自从首次发明在双子叶植
The Tanzania Field Epidemiology and Laboratory Training Program: building and transforming the public health workforce
Peter Mmbuji, David Mukanga, Janeth Mghamba, Mohamed Ahly, Fausta Mosha, Simba Azima, Sembuche Senga, Candida Moshiro, Innocent Semali, Italia Rolle, Stefan Wiktor, Suzzane McQueen, Peter McElroy, Peter Nsubuga
Pan African Medical Journal , 2011,
Abstract: The Tanzania Field Epidemiology and Laboratory Training Program (TFELTP) was established in 2008 as a partnership among the Ministry of Health and Social Welfare (MOHSW), Muhimbili University of Health and Allied Sciences, National Institute for Medical Research, and local and international partners. TFELTP was established to strengthen the capacity of MOHSW to conduct public health surveillance and response, manage national disease control and prevention programs, and to enhance public health laboratory support for surveillance, diagnosis, treatment and disease monitoring. TFELTP is a 2-year full-time training program with approximately 25% time spent in class, and 75% in the field. TFELTP offers two tracks leading to an MSc degree in either Applied Epidemiology or, Epidemiology and Laboratory Management. Since 2008, the program has enrolled a total of 33 trainees (23 males, 10 females). Of these, 11 were enrolled in 2008 and 100% graduated in 2010. All 11 graduates of cohort 1 are currently employed in public health positions within the country. Demand for the program as measured by the number of applicants has grown from 28 in 2008 to 56 in 2011. While training the public health leaders of the country, TFELTP has also provided essential service to the country in responding to high-profile disease outbreaks, and evaluating and improving its public health surveillance systems and diseases control programs. TFELTP was involved in the country assessment of the revised International Health Regulations (IHR) core capabilities, development of the Tanzania IHR plan, and incorporation of IHR into the revised Tanzania Integrated Disease Surveillance and Response (IDSR) guidelines. TFELTP is training a competent core group of public health leaders for Tanzania, as well as providing much needed service to the MOHSW in the areas of routine surveillance, outbreak detection and response, and disease program management. However, the immediate challenges that the program must address include development of a full range of in-country teaching capacity for the program, as well as a career path for graduates. Pan African Medical Journal 2011;10(Supp1):9
Susceptibility to anchoring effects
Todd McElroy,Keith Dowd
Judgment and Decision Making , 2007,
Abstract: Previous research on anchoring has shown this heuristic to be a very robust psychological phenomenon ubiquitous across many domains of human judgment and decision-making. Despite the prevalence of anchoring effects, researchers have only recently begun to investigate the underlying factors responsible for how and in what ways a person is susceptible to them. This paper examines how one such factor, the Big-Five personality trait of openness-to-experience, influences the effect of previously presented anchors on participants' judgments. Our findings indicate that participants high in openness-to-experience were significantly more influenced by anchoring cues relative to participants low in this trait. These findings were consistent across two different types of anchoring tasks providing convergent evidence for our hypothesis.
Action orientation, consistency and feelings of regret
Todd McElroy,Keith Dowd
Judgment and Decision Making , 2007,
Abstract: Previous research has demonstrated that consistency between people's behavior and their dispositions has predictive validity for judgments of regret. Research has also shown that differences in the personality variable of action orientation can influence ability to regulate negative affect. The present set of studies was designed to investigate how both consistency factors and action-state personality orientation influence judgments of regret. In Study 1, we used a recalled life event to provide a situation in which the person had experienced either an action or inaction. Individuals with an action orientation experienced more regret for situations involving inaction (staying home) than situations involving action (going out). State-oriented individuals, however, maintained high levels of regret and did not differ in their regret ratings across either the action or inaction situations. In Study 2, participants made realistic choices involving either an action or inaction. Our findings revealed the same pattern of results: action-oriented individuals who chose an option that involved not acting (inaction) had more regret that individuals who chose an option that involved acting (action). State-oriented individuals experienced high levels of regret regardless of whether they chose to act or not to act.
Healthy choices in context
Michael McCormick,Todd McElroy
Judgment and Decision Making , 2009,
Abstract: Research has shown that framing messages in terms of benefits or detriments can have a substantial influence on intended behavior. For prevention behaviors, positively framed messages have been found to elicit stronger behavioral intentions than negatively framed messages. Research also seems to indicate that certain contextual features contribute to the persuasiveness of a message. In the present research we test how message framing, contextually presented affect and the number of argument factors interact and contribute to the persuasiveness of a health related message. Consistent with our hypothesis, we found that, in our prevention focused task, increasing the number of arguments increased behavioral intentions (BI) for positively framed messages when subjects were cued, via negative affect, to be attentive to the message. This resulted in a significant framing effect for messages with the maximum number of arguments and a negative background picture. An account of contextual influence in persuasive health messages is discussed.
Memory, Television and the Making of the BBC’s 'The Story Of Wales'
Steve Blandford,Ruth McElroy
View : Journal of European Television History and Culture , 2013,
Abstract: The production of television history programming is a rich site for examining the dynamic relationship between history and memory. This article approaches these dynamics through original, empirical research of a specific case study, BBC Wales’ The Story of Wales (Green Bay for BBC Wales 2012). It analyses the commissioning, production and presentation of a landmark national history programme within the specific context of a small nation (Wales) and provides insights into how television intervenes in the construction, revision and remembering of the national past. The role of national histories in the construction of memory and national identity is importance at a time when the legitimacy of nations and states is under question and when governmental and political settlements are under construction as is the case in the post-devolutionary United Kingdom.
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