841 resultados para Revealed preferences
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The main objective of this paper is to analyse the value of information contained in prices of options on the IBEX 35 index at the Spanish Stock Exchange Market. The forward looking information is extracted using implied risk-neutral density functions estimated by a mixture of two-lognormals and three alternative risk-adjustments: the classic power and exponential utility functions and a habit-based specification that allows for a counter-cyclical variation of risk aversion. Our results show that at four-week horizon we can reject the hypothesis that between October 1996 and March 2000 the risk-neutral densities provide accurate predictions of the distributions of future realisations of the IBEX 35 index at a four-week horizon. When forecasting through risk-adjusted densities the performance of this period is statistically improved and we no longer reject that hypothesis. All risk-adjusted densities generate similar forecasting statistics. Then, at least for a horizon of four-weeks, the actual risk adjustment does not seem to be the issue. By contrast, at the one-week horizon risk-adjusted densities do not improve the forecasting ability of the risk-neutral counterparts.
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10 p.
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Using a model of an optimizing monetary authority which has preferences that weigh inflation and unemployment, Ruge-Murcia (2003, 2004) finds empirical evidence that the authority has asymmetric preferences for unemployment. We extend this model to weigh inflation and output and show that the empirical evidence using these series also supports an asymmetric preference hypothesis, only in our case, preferences are asymmetric for output. We also find evidence that the monetary authority targets potential output rather than some higher output level as would be the case in an extended Barro and Gordon (1983) model.
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The aim of this study was to understand the current and historic market situation for inland fish and it’s substitutes in order to identify which of the various production opportunities presented by the seasonal tank resource might have greatest relevance for marginal communities in the Dry-zone. Regional and sub-regional market networks for fish and meat products were investigated, ranking and scoring exercises used to characterise consumer demand in rain-fed areas of North West Province and secondary data sources were used to assess historic patterns of demand and supply [PDF contains 57 pages]
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In this paper we address several issues related to collective dichotomous decision-making by means of quaternary voting rules, i.e., when voters may choose between four actions: voting yes, voting no, abstaining and not turning up-which are aggregated by a voting rule into a dichotomous decision: acceptance or rejection of a proposal. In particular we study the links between the actions and preferences of the actors. We show that quaternary rules (unlike binary rules, where only two actions -yes or no- are possible) leave room for "manipulability" (i.e., strategic behaviour). Thus a preference profile does not in general determine an action profile. We also deal with the notions of success and decisiveness and their ex ante assessment for quaternary voting rules, and discuss the role of information and coordination in this context.
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As coastal destinations continue to grow, due to tourism and residential expansion, the demand for public beach access and related amenities will also increase. As a resultagencies that provide beach access and related amenities face challenges when considering both residents and visitors use beaches and likely possess different needs, as well as different preferences for management decisions. Being a resident of a coastal county provides more opportunity to use local beaches, but coastal tourism is an important and growing economic engine in coastal communities (Kriesel, Landry, & Keeler, 2005; Pogue & Lee, 1999). Therefore, providing agencies with a comprehensive assessment of the differences between these two groups will increase the likelihood of effective management programs and policies for the provision of public beach access and related amenities. The purpose of this paper was to use a stated preference choice method (SPCM) to identify the extent of both residents’ and visitors’ preferences for public beach management options. (PDF contains 4 pages)
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The genomes of many positive stranded RNA viruses and of all retroviruses are translated as large polyproteins which are proteolytically processed by cellular and viral proteases. Viral proteases are structurally related to two families of cellular proteases, the pepsin-like and trypsin-like proteases. This thesis describes the proteolytic processing of several nonstructural proteins of dengue 2 virus, a representative member of the Flaviviridae, and describes methods for transcribing full-length genomic RNA of dengue 2 virus. Chapter 1 describes the in vitro processing of the nonstructural proteins NS2A, NS2B and NS3. Chapter 2 describes a system that allows identification of residues within the protease that are directly or indirectly involved with substrate recognition. Chapter 3 describes methods to produce genome length dengue 2 RNA from cDNA templates.
The nonstructural protein NS3 is structurally related to viral trypsinlike proteases from the alpha-, picorna-, poty-, and pestiviruses. The hypothesis that the flavivirus nonstructural protein NS3 is a viral proteinase that generates the termini of several nonstructural proteins was tested using an efficient in vitro expression system and antisera specific for the nonstructural proteins NS2B and NS3. A series of cDNA constructs was transcribed using T7 RNA polymerase and the RNA translated in reticulocyte lysates. Proteolytic processing occurred in vitro to generate NS2B and NS3. The amino termini of NS2B and NS3 produced in vitro were found to be the same as the termini of NS2B and NS3 isolated from infected cells. Deletion analysis of cDNA constructs localized the protease domain necessary and sufficient for correct cleavage to the first 184 amino acids of NS3. Kinetic analysis of processing events in vitro and experiments to examine the sensitivity of processing to dilution suggested that an intramolecular cleavage between NS2A and NS2B preceded an intramolecular cleavage between NS2B and NS3. The data from these expression experiments confirm that NS3 is the viral proteinase responsible for cleavage events generating the amino termini of NS2B and NS3 and presumably for cleavages generating the termini of NS4A and NS5 as well.
Biochemical and genetic experiments using viral proteinases have defined the sequence requirements for cleavage site recognition, but have not identified residues within proteinases that interact with substrates. A biochemical assay was developed that could identify residues which were important for substrate recognition. Chimeric proteases between yellow fever and dengue 2 were constructed that allowed mapping of regions involved in substrate recognition, and site directed mutagenesis was used to modulate processing efficiency.
Expression in vitro revealed that the dengue protease domain efficiently processes the yellow fever polyprotein between NS2A and NS2B and between NS2B and NS3, but that the reciprocal construct is inactive. The dengue protease processes yellow fever cleavage sites more efficiently than dengue cleavage sites, suggesting that suboptimal cleavage efficiency may be used to increase levels of processing intermediates in vivo. By mutagenizing the putative substrate binding pocket it was possible to change the substrate specificity of the yellow fever protease; changing a minimum of three amino acids in the yellow fever protease enabled it to recognize dengue cleavage sites. This system allows identification of residues which are directly or indirectly involved with enzyme-substrate interaction, does not require a crystal structure, and can define the substrate preferences of individual members of a viral proteinase family.
Full-length cDNA clones, from which infectious RNA can be transcribed, have been developed for a number of positive strand RNA viruses, including the flavivirus type virus, yellow fever. The technology necessary to transcribe genomic RNA of dengue 2 virus was developed in order to better understand the molecular biology of the dengue subgroup. A 5' structural region clone was engineered to transcribe authentic dengue RNA that contains an additional 1 or 2 residues at the 5' end. A 3' nonstructural region clone was engineered to allow production of run off transcripts, and to allow directional ligation with the 5' structural region clone. In vitro ligation and transcription produces full-length genomic RNA which is noninfectious when transfected into mammalian tissue culture cells. Alternative methods for constructing cDNA clones and recovering live dengue virus are discussed.
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Time, risk, and attention are all integral to economic decision making. The aim of this work is to understand those key components of decision making using a variety of approaches: providing axiomatic characterizations to investigate time discounting, generating measures of visual attention to infer consumers' intentions, and examining data from unique field settings.
Chapter 2, co-authored with Federico Echenique and Kota Saito, presents the first revealed-preference characterizations of exponentially-discounted utility model and its generalizations. My characterizations provide non-parametric revealed-preference tests. I apply the tests to data from a recent experiment, and find that the axiomatization delivers new insights on a dataset that had been analyzed by traditional parametric methods.
Chapter 3, co-authored with Min Jeong Kang and Colin Camerer, investigates whether "pre-choice" measures of visual attention improve in prediction of consumers' purchase intentions. We measure participants' visual attention using eyetracking or mousetracking while they make hypothetical as well as real purchase decisions. I find that different patterns of visual attention are associated with hypothetical and real decisions. I then demonstrate that including information on visual attention improves prediction of purchase decisions when attention is measured with mousetracking.
Chapter 4 investigates individuals' attitudes towards risk in a high-stakes environment using data from a TV game show, Jeopardy!. I first quantify players' subjective beliefs about answering questions correctly. Using those beliefs in estimation, I find that the representative player is risk averse. I then find that trailing players tend to wager more than "folk" strategies that are known among the community of contestants and fans, and this tendency is related to their confidence. I also find gender differences: male players take more risk than female players, and even more so when they are competing against two other male players.
Chapter 5, co-authored with Colin Camerer, investigates the dynamics of the favorite-longshot bias (FLB) using data on horse race betting from an online exchange that allows bettors to trade "in-play." I find that probabilistic forecasts implied by market prices before start of the races are well-calibrated, but the degree of FLB increases significantly as the events approach toward the end.
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International fisheries agencies recommend exploitation paths that satisfy two features. First, for precautionary reasons exploitation paths should avoid high fishing mortality in those fisheries where the biomass is depleted to a degree that jeopardise the stock's capacity to produce the Maximum Sustainable Yield (MSY). Second, for economic and social reasons, captures should be as stable (smooth) as possible over time. In this article we show that a conflict between these two interests may occur when seeking for optimal exploitation paths using age structured bioeconomic approach. Our results show that this conflict be overtaken by using non constant discount factors that value future stocks considering their relative intertemporal scarcity.
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É alta a prevalência de dor crônica em pacientes com câncer, que é comprovadamente associada ao sofrimento psicológico acentuado e muitas vezes não é adequadamente diagnosticada e tratada. Estudo que realizamos com 120 pacientes adultos em atendimento ambulatorial na Clínica de Dor do Instituto Nacional de Câncer, no Rio de Janeiro que demonstrou que os pacientes mesmo conhecendo o seu diagnóstico de câncer, não se sentiam informados sobre a doença e a dor oncológica a contento, o que trazia insatisfação com o tratamento recebido e maior exigência com os resultados do mesmo. Nosso estudo revelou, ainda, que o comportamento do profissional durante o atendimento pode ser percebido pelos pacientes como fator tanto de melhora como de piora da dor, sendo o comportamento atencioso do profissional muitas vezes mais valorizado pelos pacientes que a supressão da dor. Estes resultados suscitaram questões relativas à qualidade da interação entre médicos e pacientes, desenvolvidas nesta dissertação. Embora não sejam suficientemente investidas nem na relação médico-paciente, nem na educação e no treinamento profissional, as habilidades de comunicação do médico afetam diretamente o nível de informação e de satisfação do paciente, suas crenças e os resultados do tratamento. Ao longo do tempo a relação médico paciente vem mudando, deixando de ser tão centrada na doença e no médico, para centrar-se mais no doente como um ser integral, o que implica no reconhecimento, pelo médico, de saberes diferentes dos seus e de que o seu saber não constitui uma verdade absoluta a ser acatada pelos demais. Apesar de bem-vindas, estas mudanças trazem uma certa confusão nos papéis a serem desempenhados por médicos e pacientes e dificuldades aos médicos de lidarem com as diferenças, com as queixas subjetivas dos pacientes, com as emoções destes e as suas próprias. Se hoje é esperado que os pacientes sejam participativos, corresponsáveis por seus tratamentos e recuperação e que se deem conta do poder que eles têm, individual e coletivamente, espera-se que os médicos sejam estudiosos, bem informados, experientes, sinceros, empáticos, sensíveis, atenciosos, compassivos, perspicazes, bem treinados, hábeis em compartilhar informações e decisões com os pacientes, compreendendo o que estes querem e o que não querem e ajudando-os a expressar suas crenças, preferências e receios, disponibilizando tempo suficiente para isso. Tantas expectativas terminam por trazer conflitos que só poderão ser resolvidos com a melhoria da comunicação entre médicos e pacientes, num esforço de ambas as partes.
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Thirty-three skipjack tuna (Katsuwonus pelamis) (53−73 cm fork length) were caught and released with implanted archival tags in the eastern equatorial Pacific Ocean during April 2004. Six skipjack tuna were recap-tured, and 9.3 to 10.1 days of depth and temperature data were down-loaded from five recovered tags. The vertical habitat-use distributions indicated that skipjack tuna not associated with floating objects spent 98.6% of their time above the thermocline (depth=44 m) during the night, but spent 37.7% of their time below the thermocline during the day. When not associated with floating objects, skipjack tuna displayed repetitive bounce-diving behavior to depths between 50 and 300 m during the day. The deepest dive recorded was 596 m, where the ambient temperature was 7.7°C. One dive was particularly remarkable because the fish contin-uously swam for 2 hours below the thermocline to a maximum depth of 330 m. During that dive, the ambient temperature reached a low of 10.5°C, and the peritoneal cavity temperature reached a low of 15.9°C. The vertical movements and habitat use of skipjack tuna, revealed in this study, provide a much greater understanding of their ecological niche and catchability by purse-seine fisheries.