161 resultados para Empirical asset pricing


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We develop a two-sided matching model to analyze collaboration between heterogeneousacademics and firms. We predict a positive assortative matching in terms of both scientificability and affinity for type of research, but negative assortative in terms of ability on one sideand affinity in the other. In addition, the most able and most applied academics and the mostable and most basic firms shall collaborate rather than stay independent. Our predictionsreceive strong support from the analysis of the teams of academics and firms that proposeresearch projects to the UK's Engineering and Physical Sciences Research Council.

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I examine the impact of alternative monetary policy rules on arational asset price bubble, through the lens of an overlapping generations model with nominal rigidities. A systematic increase in interestrates in response to a growing bubble is shown to enhance the fluctuations in the latter, through its positive effect on bubble growth. Theoptimal monetary policy seeks to strike a balance between stabilization of the bubble and stabilization of aggregate demand. The paper'smain findings call into question the theoretical foundations of the casefor "leaning against the wind" monetary policies.

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The interest in solar ultraviolet (UV) radiation from the scientific community and the general population has risen significantly in recent years because of the link between increased UV levels at the Earth's surface and depletion of ozone in the stratosphere. As a consequence of recent research, UV radiation climatologies have been developed, and effects of some atmospheric constituents (such as ozone or aerosols) have been studied broadly. Correspondingly, there are well-established relationships between, for example, total ozone column and UV radiation levels at the Earth's surface. Effects of clouds, however, are not so well described, given the intrinsic difficulties in properly describing cloud characteristics. Nevertheless, the effect of clouds cannot be neglected, and the variability that clouds induce on UV radiation is particularly significant when short timescales are involved. In this review we show, summarize, and compare several works that deal with the effect of clouds on UV radiation. Specifically, works reviewed here approach the issue from the empirical point of view: Some relationship between measured UV radiation in cloudy conditions and cloud-related information is given in each work. Basically, there are two groups of methods: techniques that are based on observations of cloudiness (either from human observers or by using devices such as sky cameras) and techniques that use measurements of broadband solar radiation as a surrogate for cloud observations. Some techniques combine both types of information. Comparison of results from different works is addressed through using the cloud modification factor (CMF) defined as the ratio between measured UV radiation in a cloudy sky and calculated radiation for a cloudless sky. Typical CMF values for overcast skies range from 0.3 to 0.7, depending both on cloud type and characteristics. Despite this large dispersion of values corresponding to the same cloud cover, it is clear that the cloud effect on UV radiation is 15–45% lower than the cloud effect on total solar radiation. The cloud effect is usually a reducing effect, but a significant number of works report an enhancement effect (that is increased UV radiation levels at the surface) due to the presence of clouds. The review concludes with some recommendations for future studies aimed to further analyze the cloud effects on UV radiation

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La tècnica de l’electroencefalograma (EEG) és una de les tècniques més utilitzades per estudiar el cervell. En aquesta tècnica s’enregistren els senyals elèctrics que es produeixen en el còrtex humà a través d’elèctrodes col•locats al cap. Aquesta tècnica, però, presenta algunes limitacions a l’hora de realitzar els enregistraments, la principal limitació es coneix com a artefactes, que són senyals indesitjats que es mesclen amb els senyals EEG. L’objectiu d’aquest treball de final de màster és presentar tres nous mètodes de neteja d’artefactes que poden ser aplicats en EEG. Aquests estan basats en l’aplicació de la Multivariate Empirical Mode Decomposition, que és una nova tècnica utilitzada per al processament de senyal. Els mètodes de neteja proposats s’apliquen a dades EEG simulades que contenen artefactes (pestanyeigs), i un cop s’han aplicat els procediments de neteja es comparen amb dades EEG que no tenen pestanyeigs, per comprovar quina millora presenten. Posteriorment, dos dels tres mètodes de neteja proposats s’apliquen sobre dades EEG reals. Les conclusions que s’han extret del treball són que dos dels nous procediments de neteja proposats es poden utilitzar per realitzar el preprocessament de dades reals per eliminar pestanyeigs.

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El estudio de las variables relacionadas con la adquisición de las lenguas escolares en contextos bilingües y multilingües ha resurgido a raíz de la incorporación de alumnado extranjero al sistema educativo español. En este sentido, y gracias a su peculiar situación sociolingüística, Cataluña se ha convertido en un observatorio perfecto para estudiar el proceso de adquisición de lenguas del alumnado extranjero. En este artículo presentamos una parte de los datos obtenidos en la evaluación del conocimiento de catalán y del castellano de 668 alumnos extranjeros de sexto de Primaria escolarizados en 57 centros de Cataluña. Con ello pretendemos estudiar los efectos de la presencia y del uso social de las lenguas escolares en el conocimiento lingüístico de este alumnado. La hipótesis principal es que el desarrollo de buenos niveles de conocimiento escrito de las lenguas escolares por parte de los alumnos extranjeros depende, en buena medida, de las oportunidades que haya en el entorno social para que ellos puedan utilizar estas lenguas en los intercambios comunicativos informales con sus compañeros o con otros adultos. Las conclusiones del trabajo señalan las relaciones existentes entre el desarrollo de habilidades lingüísticas conversacionales y el de habilidades lingüísticas cognitivo-académicas (Cummins, 1979b), en el sentido de que tanto el conocimiento escrito de catalán como el de castellano que tiene el alumnado extranjero están condicionados por el nivel de desarrollo conversacional previo en ambas lenguas. Además, apuntan a que la transferencia de habilidades lingüísticas cognitivo-académicas no se produce directamente entre el catalán y el castellano, sino que depende fundamentalmente de la presencia social que tengan estas lenguas y de sus usos informales. Así, en la medida en que un buen número de estudiantes extranjeros no desarrolla suficiente competencia lingüística conversacional ni en catalán ni en castellano, el proceso de adquisición de las lenguas escolares se alarga más allá de los seis años

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This article reviews previous research regarding cost stickiness and performs an empirical analysis applied to a sample of farms. It recognizes that modelization of cost stickiness is a particular case of representation of cost variations as a function of output variations. It also discusses methodological issues and analyses cost stickiness for all registered farm costs and opportunity costs of family work. Costs exhibit a considerable level of rigidity. Even for variable costs, a decrease in activity involves a lower decrease in costs than the amounts involved when activity increases. While registered indirect costs slightly decrease when activity decreases, opportunity costs always increase. The study provides empirical evidence that cost stickiness is significantly reduced with better management decision practices.

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Recent theoretical models of economic growth have emphasised the role of external effects on the accumulation of factors of production. Although most of the literature has considered the externalities across firms within a region, in this paper we go a step further and consider the possibility that these externalities cross the barriers of regional economies. We assess the role of these external effects in explaining growth and economic convergence. We present a simple growth model, which includes externalities across economies, developing a methodology for testing their existence and estimating their strength. In our view, spatial econometrics is naturally suited to an empirical consideration of these externalities. We obtain evidence on the presence of significant externalities both across Spanish and European regions.

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In this paper we examine the effect of tax policy on the relationship between inequality and growth in a two-sector non-scale model. With non-scale models, the longrun equilibrium growth rate is determined by technological parameters and it is independent of macroeconomic policy instruments. However, this fact does not imply that fiscal policy is unimportant for long-run economic performance. It indeed has important effects on the different levels of key economic variables such as per capita stock of capital and output. Hence, although the economy grows at the same rate across steady states, the bases for economic growth may be different.The model has three essential features. First, we explicitly model skill accumulation, second, we introduce government finance into the production function, and we introduce an income tax to mirror the fiscal events of the 1980¿s and 1990¿s in the US. The fact that the non-scale model is associated with higher order dynamics enables it to replicate the distinctly non-linear nature of inequality in the US with relative ease. The results derived in this paper attract attention to the fact that the non-scale growth model does not only fit the US data well for the long-run (Jones, 1995b) but also that it possesses unique abilities in explaining short term fluctuations of the economy. It is shown that during transition the response of the relative simulated wage to changes in the tax code is rather non-monotonic, quite in accordance to the US inequality pattern in the 1980¿s and early 1990¿s.More specifically, we have analyzed in detail the dynamics following the simulation of an isolated tax decrease and an isolated tax increase. So, after a tax decrease the skill premium follows a lower trajectory than the one it would follow without a tax decrease. Hence we are able to reduce inequality for several periods after the fiscal shock. On the contrary, following a tax increase, the evolution of the skill premium remains above the trajectory carried on by the skill premium under a situation with no tax increase. Consequently, a tax increase would imply a higher level of inequality in the economy

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This paper tests some hypothesis about the determinants of the local tax structure. In particular, we focus on the effects that the property tax deductibility in the national income tax has on the relative use of the property tax and user charges. We deal with the incentive effects that local governments face regarding the different sources of revenue by means of a model in which the local tax structure and the level of public expenditure arise as a result of the maximizing behaviour of local politicians subject to the economic effects of the tax system. We attempt to test the hypothesis developed with data corresponding to a set of Spanish municipalities during the period 1987-9l. We find that tax deductibility provides incentives to raise revenues from the property tax but does not introduce a biass against user charges or in favor of overall spending growth

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This article reviews previous research regarding cost stickiness and performs an empirical analysis applied to a sample of farms. It recognizes that modelization of cost stickiness is a particular case of representation of cost variations as a function of output variations. It also discusses methodological issues and analyses cost stickiness for all registered farm costs and opportunity costs of family work. Costs exhibit a considerable level of rigidity. Even for variable costs, a decrease in activity involves a lower decrease in costs than the amounts involved when activity increases. While registered indirect costs slightly decrease when activity decreases, opportunity costs always increase. The study provides empirical evidence that cost stickiness is significantly reduced with better management decision practices.

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Recent theoretical models of economic growth have emphasised the role of external effects on the accumulation of factors of production. Although most of the literature has considered the externalities across firms within a region, in this paper we go a step further and consider the possibility that these externalities cross the barriers of regional economies. We assess the role of these external effects in explaining growth and economic convergence. We present a simple growth model, which includes externalities across economies, developing a methodology for testing their existence and estimating their strength. In our view, spatial econometrics is naturally suited to an empirical consideration of these externalities. We obtain evidence on the presence of significant externalities both across Spanish and European regions.

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In this paper we examine the effect of tax policy on the relationship between inequality and growth in a two-sector non-scale model. With non-scale models, the longrun equilibrium growth rate is determined by technological parameters and it is independent of macroeconomic policy instruments. However, this fact does not imply that fiscal policy is unimportant for long-run economic performance. It indeed has important effects on the different levels of key economic variables such as per capita stock of capital and output. Hence, although the economy grows at the same rate across steady states, the bases for economic growth may be different.The model has three essential features. First, we explicitly model skill accumulation, second, we introduce government finance into the production function, and we introduce an income tax to mirror the fiscal events of the 1980¿s and 1990¿s in the US. The fact that the non-scale model is associated with higher order dynamics enables it to replicate the distinctly non-linear nature of inequality in the US with relative ease. The results derived in this paper attract attention to the fact that the non-scale growth model does not only fit the US data well for the long-run (Jones, 1995b) but also that it possesses unique abilities in explaining short term fluctuations of the economy. It is shown that during transition the response of the relative simulated wage to changes in the tax code is rather non-monotonic, quite in accordance to the US inequality pattern in the 1980¿s and early 1990¿s.More specifically, we have analyzed in detail the dynamics following the simulation of an isolated tax decrease and an isolated tax increase. So, after a tax decrease the skill premium follows a lower trajectory than the one it would follow without a tax decrease. Hence we are able to reduce inequality for several periods after the fiscal shock. On the contrary, following a tax increase, the evolution of the skill premium remains above the trajectory carried on by the skill premium under a situation with no tax increase. Consequently, a tax increase would imply a higher level of inequality in the economy

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Several European telecommunications regulatory agencies have recently introduced a fixed capacity charge (flat rate) to regulate access to the incumbent's network. The purpose of this paper is to show that the optimal capacity charge and the optimal access-minute charge analysed by Armstrong, Doyle, and Vickers (1996) have a similar structure and imply the same payment for the entrant. I extend the analysis tothe case where there is a competitor with market power. In this case, the optimalcapacity charge should be modified to avoid that the entrant cream-skims the market,fixing a longer or a shorter peak period than the optimal. Finally, I consider a multiproduct setting, where the effect of the product differentiation is exacerbated.

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This paper tests some hypothesis about the determinants of the local tax structure. In particular, we focus on the effects that the property tax deductibility in the national income tax has on the relative use of the property tax and user charges. We deal with the incentive effects that local governments face regarding the different sources of revenue by means of a model in which the local tax structure and the level of public expenditure arise as a result of the maximizing behaviour of local politicians subject to the economic effects of the tax system. We attempt to test the hypothesis developed with data corresponding to a set of Spanish municipalities during the period 1987-9l. We find that tax deductibility provides incentives to raise revenues from the property tax but does not introduce a biass against user charges or in favor of overall spending growth

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This work carries out an empirical evaluation of the impact of the main mechanism for regulating the prices of medicines in the UK on a variety ofpharmaceutical price indices. The empirical evidence shows that the overall impact of the rate of return cap appears to have been slight or even null, and in any case that the impact would differ across therapeutic areas. These empiricalfindings suggest that the price regulation has managed to encourage UK-based firms¿ diversification in many therapeutic areas