871 resultados para Panel data probit model


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Ocean–sea ice reanalyses are crucial for assessing the variability and recent trends in the Arctic sea ice cover. This is especially true for sea ice volume, as long-term and large scale sea ice thickness observations are inexistent. Results from the Ocean ReAnalyses Intercomparison Project (ORA-IP) are presented, with a focus on Arctic sea ice fields reconstructed by state-of-the-art global ocean reanalyses. Differences between the various reanalyses are explored in terms of the effects of data assimilation, model physics and atmospheric forcing on properties of the sea ice cover, including concentration, thickness, velocity and snow. Amongst the 14 reanalyses studied here, 9 assimilate sea ice concentration, and none assimilate sea ice thickness data. The comparison reveals an overall agreement in the reconstructed concentration fields, mainly because of the constraints in surface temperature imposed by direct assimilation of ocean observations, prescribed or assimilated atmospheric forcing and assimilation of sea ice concentration. However, some spread still exists amongst the reanalyses, due to a variety of factors. In particular, a large spread in sea ice thickness is found within the ensemble of reanalyses, partially caused by the biases inherited from their sea ice model components. Biases are also affected by the assimilation of sea ice concentration and the treatment of sea ice thickness in the data assimilation process. An important outcome of this study is that the spatial distribution of ice volume varies widely between products, with no reanalysis standing out as clearly superior as compared to altimetry estimates. The ice thickness from systems without assimilation of sea ice concentration is not worse than that from systems constrained with sea ice observations. An evaluation of the sea ice velocity fields reveals that ice drifts too fast in most systems. As an ensemble, the ORA-IP reanalyses capture trends in Arctic sea ice area and extent relatively well. However, the ensemble can not be used to get a robust estimate of recent trends in the Arctic sea ice volume. Biases in the reanalyses certainly impact the simulated air–sea fluxes in the polar regions, and questions the suitability of current sea ice reanalyses to initialize seasonal forecasts.

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What explains the cross-national variation in inflation rates in developed countries? Previous literature has emphasised the role of ideas and institutions, and to a lesser extent interest groups, while leaving the role of electoral politics comparatively unexplored. This paper seeks to redress this neglect by focusing on one case where electoral politics matters for inflation: the share of the population above 65 years old in a country. I argue that countries with a larger share of elderly have lower inflation because older people are both more inflation averse and politically powerful, forcing governments to pursue lower inflation. I test my argument in three steps. First, logistic regression analysis of survey data confirms older people are more inflation averse. Second, panel data regression analysis of party manifesto data reveals that European countries with more old people have more economically orthodox political parties. Third, time series cross-section regression analyses demonstrate that the share of the elderly is negatively correlated with inflation in both a sample of 21 advanced OECD economies and a larger sample of 175 countries. Ageing may therefore push governments to adopt a low inflation regime.

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Following the 1997 crisis, banking sector reforms in Asia have been characterised by the emphasis on prudential regulation, associated with increased financial liberalisation. Using a panel data set of commercial banks from eight major Asian economies over the period 2001-2010, this study explores how the coexistence of liberalisation and prudential regulation affects banks’ cost characteristics. Given the presence of heterogeneity of technologies across countries, we use a stochastic frontier approach followed by the estimation of a deterministic meta-frontier to provide ‘true’ estimates of bank cost efficiency measures. Our results show that the liberalization of bank interest rates and the increase in foreign banks' presence have had a positive and significant impact on technological progress and cost efficiency. On the other hand, we find that prudential regulation might adversely affect bank cost performance. When designing an optimal regulatory framework, policy makers should combine policies which aim to foster financial stability without hindering financial intermediation.

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In this paper, we study the variations of groups (galaxy properties according to the assembly history in Sloan Digital Sky Survey Data Release 6 (SDSS-DR6) selected groups. Using mock SDSS group catalogues, we find two suitable indicators of group formation time: (i) the isolation of the group, defined as the distance to the nearest neighbour ill terms of its virial radius and 00 the concentration. measured as the groups inner density calculated using the fifth nearest bright galaxy to the groups centre. Groups Within narrow ranges of Mass ill the mock catalO-Lie show increasing Ifl-OLIP alle With isolation and concentration. However, in the observational data the stellar age, as indicated by the spectral type, only shows a correlation with concentration. We study groups of similar mass and different assembly history. finding important differences ill their galaxy population. Particularly, ill high-mass SDSS groups. the number of members. mass-to-light ratios, red galaxy fractions and the magnitude difference between the brightest and second-brightest group galaxies, show different trends as a function of isolation and concentration, even when it is expected that the latter two quantities correlate with group age. Conversely. low-mass SDSS groups appear to be less sensitive to their assembly history. The correlations detected in the SDSS are not consistent with the trends measured in the mock catalogues. However, discrepancies can he explained in terms of the disagreement found in the a-e-isolation trends, suggesting that the model might be overestimating the effects of, environment, We discuss how the modelling of the cold gas ill satellite galaxies could be responsible for this problem. These results call be Used to improve our Understanding of the evolution of galaxies ill high-density environments.

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In the quantum Hall regime, the longitudinal resistivity rho (xx) plotted as a density-magnetic-field (n (2D) -B) diagram displays ringlike structures due to the crossings of two sets of spin split Landau levels from different subbands [see, e.g., Zhang et al., in Phys. Rev. Lett. 95:216801, 2005. For tilted magnetic fields, some of these ringlike structures ""shrink"" as the tilt angle is increased and fully collapse at theta (c) a parts per thousand 6A degrees. Here we theoretically investigate the topology of these structures via a non-interacting model for the 2DEG. We account for the inter Landau-level coupling induced by the tilted magnetic field via perturbation theory. This coupling results in anticrossings of Landau levels with parallel spins. With the new energy spectrum, we calculate the corresponding n (2D) -B diagram of the density of states (DOS) near the Fermi level. We argue that the DOS displays the same topology as rho (xx) in the n (2D) -B diagram. For the ring with filling factor nu=4, we find that the anticrossings make it shrink for increasing tilt angles and collapse at a large enough angle. Using effective parameters to fit the theta=0A degrees data, we find a collapsing angle theta (c) a parts per thousand 3.6A degrees. Despite this factor-of-two discrepancy with the experimental data, our model captures the essential mechanism underlying the ring collapse.

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Gross domestic product (GDP) is generally considered as the most important index and comprehensive measure of the size of economy. This paper investigates empirically the relationship between transport infrastructure (focus on highways) and GDP growth based on a production function approach. The physical stocks of transport infrastructure were used instead of monetary data to measure public capital together with several other variables (labor and private capital) that were hypothesized to affect economic growth. Then we explore a number of subsequent studies that use panel data covering the period between 1992 and 2004. An investigation was done to compare developed countries and developing countries. Results indicate that physical units are positively and significantly related to economic growth. Furthermore there was an interesting finding that the output elasticity with respect to physical units for developed countries is higher than developing countries.

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Using a physically based model, the microstructural evolution of Nb microalloyed steels during rolling in SSAB Tunnplåt’s hot strip mill was modeled. The model describes the evolution of dislocation density, the creation and diffusion of vacancies, dynamic and static recovery through climb and glide, subgrain formation and growth, dynamic and static recrystallization and grain growth. Also, the model describes the dissolution and precipitation of particles. The impeding effect on grain growth and recrystallization due to solute drag and particles is accounted for. During hot strip rolling of Nb steels, Nb in solid solution retards recrystallization due to solute drag and at lower temperatures strain-induced precipitation of Nb(C,N) may occur which effectively retard recrystallization. The flow stress behavior during hot rolling was calculated where the mean flow stress values were calculated using both the model and measured mill data. The model showed that solute drag has an essential effect on recrystallization during hot rolling of Nb steels.

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Using data from 2000-2011, the effects of a new IKEA store on retail revenues, employment, and inflow of purchasing power in the entry municipalities, as well as in neighboring municipalities were investigated. A propensity score matching method was used to find non IKEA entry municipalities that were as similar as possible to the entry municipalities based on the situation before entry. Our results indicate that IKEA-entry increased entry-municipality durable-goods revenues by about 20% and employment by about 17%. Only small and, in most cases, statistically insignificant effects were found in neighboring municipalities.

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We consider method of moment fixed effects (FE) estimation of technical inefficiency. When N, the number of cross sectional observations, is large it ispossible to obtain consistent central moments of the population distribution of the inefficiencies. It is well-known that the traditional FE estimator may be seriously upward biased when N is large and T, the number of time observations, is small. Based on the second central moment and a single parameter distributional assumption on the inefficiencies, we obtain unbiased technical inefficiencies in large N settings. The proposed methodology bridges traditional FE and maximum likelihood estimation – bias is reduced without the random effects assumption.

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IKEA is one of the world’s largest retailers, but little is known about how IKEA impact incumbent retailers when deciding to enter a local market. Previous studies on the effects of big-box entry on surrounding retailers have also generated inconclusive results, and mainly been focused towards entry of Wal-Mart in the United States. We contribute to this literature by investigating the effects of IKEA entry on revenues and employment for incumbent retail firms in three Swedish municipalities during 2000-2010. Our results indicate that a new IKEA store increases average revenues for incumbent retailers within the entry municipality by 11%, but also that the effect is highly heterogeneous within the municipality. Retailers that were located up to 1 km from IKEA experienced a 26% increase in revenues when IKEA entered the municipality. However, the positive spillover effect of a new IKEA store on retail revenues diminished with the distance to IKEA, and turned insignificant for retailers in the city centers and those that were located 5-10 km from IKEA. The effects on employment were much less pronounced, and in most cases statistically insignificant.

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Vertical stream bed erosion has been studied routinely and its modeling is getting widespread acceptance. The same cannot be said with lateral stream bank erosion since its measurement or numerical modeling is very challenging. Bank erosion, however, can be important to channel morphology. It may contribute significantly to the overall sediment budget of a stream, is a leading cause of channel migration, and is the cause of major channel maintenance. However, combined vertical and lateral channel evolution is seldom addressed. In this study, a new geofluival numerical model is developed to simulate combined vertical and lateral channel evolution. Vertical erosion is predicted with a 2D depth-averaged model SRH-2D, while lateral erosion is simulated with a linear retreat bank erosion model developed in this study. SRH-2D and the bank erosion model are coupled together both spatially and temporally through a common mesh and the same time advancement. The new geofluvial model is first tested and verified using laboratory meander channels; good agreement are obtained between predicted bank retreat and measured data. The model is then applied to a 16-kilometer reach of Chosui River, Taiwan. Vertical and lateral channel evolution during a three-year period (2004 to 2007) is simulated and results are compared with the field data. It is shown that the geofluvial model correctly captures all major erosion and deposition patterns. The new model is shown to be useful for identifying potential erosion sites and providing information for river maintenance planning.

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Esta dissertação visa investigar a estrutura de custos do setor aéreo doméstico brasileiro. A fim de realizar essa investigação com maior detalhamento, faz-se, respectivamente, nos capítulos 1 e 2, descrições histórica e econômica desse setor. Essa investigação permitirá dar uma resposta a polêmica sobre a quantidade de empresas que esse setor comporta; além disso, fornecerá indicações de políticas públicas, para que se possa fazer uma melhor avaliação de possíveis mudanças no comportamento das empresas aéreas existentes.

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Using the Pricing Equation in a panel-data framework, we construct a novel consistent estimator of the stochastic discount factor (SDF) which relies on the fact that its logarithm is the serial-correlation ìcommon featureîin every asset return of the economy. Our estimator is a simple function of asset returns, does not depend on any parametric function representing preferences, is suitable for testing di§erent preference speciÖcations or investigating intertemporal substitution puzzles, and can be a basis to construct an estimator of the risk-free rate. For post-war data, our estimator is close to unity most of the time, yielding an average annual real discount rate of 2.46%. In formal testing, we cannot reject standard preference speciÖcations used in the literature and estimates of the relative risk-aversion coe¢ cient are between 1 and 2, and statistically equal to unity. Using our SDF estimator, we found little signs of the equity-premium puzzle for the U.S.

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Este artigo examina o impacto das recentes programas de recompra de ações sobre a expropriação de acionistas minoritários. Recentemente, houve 12 ofertas de recompra de ações cujo controle foi adquirido por investidores estratégicos estrangeiros ou por consórcios para comprar empresas privatizadas. Dois exemplos são: (i) a compra do controle da Lojas Renner, empresa de varejo da família Renner pela J. C. Penney; e (ii) Cargill comprando o controle da Solorrico, uma empresa de fertilizantes controlada por uma família. Paralelamente, a CVM emitiu a resolução #299 para evitar a expropriação de acionistas minoritários. Nós conjeturamos que pequenas e médias empresas com baixo crescimento, baixa alavancagem, e propriedade concentrada são candidatos mais prováveis para um "takeover" com maior probabilidade de expropriação. Isto explica parcialmente a falta de liquidez e o alto desconto na oferta pública de ações no mercado acionário brasileiro.

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A área de fundos de investimento tem crescido no Brasil nos últimos 7 anos. Movimento semelhante tem sido observado no percentual destinado a fundos de ações. Parte deste movimento pode ser creditado à entrada de atores sem familiaridade com o universo financeiro, mas que vislumbram neste segmento uma oportunidade para investir seu dinheiro. O desconhecimento do funcionamento do universo financeiro leva o novo investidor a eleger critérios para seleção de onde alocar os seus recursos, já que se espera que um gestor profissional faça as melhores escolhas. Segundo Chevalier & Ellison (1999), a imprensa financeira produz um grande volume e variedade de informação sobre as pessoas que gerenciam esses fundos, mas pouco se fala de seus antecedentes educacionais. Este trabalho tem como objetivo analisar se o desempenho dos fundos de ações esta relacionado com as características dos gestores desses fundos. Em particular, se estudou a relação entre o desempenho dos fundos e a formação dos gestores, a qualidade das escolas em que cursaram, bem como o fato de possuírem pós-graduação Lato Sensu ou Stricto Sensu, além da idade e seu “tempo de experiência” no mercado financeiro. Utilizamos como base os dados coletados pelo sistema QUANTUN AXIS (Quantun Avaliação de Fundos de Investimento), tendo como referência o período de setembro/2007 a 2008. Consultamos currículos dos 81 gestores da amostra por meio de buscas aos sites das empresas administradoras, consulta por telefone aos gestores, e currículos via difusores de informação como o Bloomberg. Foram então realizadas as análises Cross-Section. Para tal, foi utilizada uma corrente de investigação que analisou o impacto dos antecedentes educacionais dos gestores de fundos sobre os resultados dos mesmos nos EUA, destacando os trabalhos de Golec (1996), Chevalier & Ellison (1999) e Gottesman & Morey (2006). O resultado deste trabalho sugere que existe diferença na análise cross-sectional entre o desempenho dos fundos de ações no Brasil e a qualidade do curso de graduação do gestor. Futuras pesquisas poderiam, utilizando a mesma amostra de gestores, acompanhar a evolução dos dados do currículo em comparação ao desempenho dos fundos administrados em uma perspectiva temporal utilizando dados de painel.