Parametric and semiparametric estimation of sample selection models: an empirical application to the female labour force in Portugal

This comment corrects the errors in the estimation process that appear in Martins (2001). The first error is in the parametric probit estimation, as the previously presented results do not maximize the log-likelihood function. In the global maximum more variables become significant. As for the semiparametric estimation method, the kernel function used in Martins (2001) can take on both positive and negative values, which implies that the participation probability estimates may be outside the interval [0,1]. We have solved the problem by applying local smoothing in the kernel estimation, as suggested by Klein and Spady (1993).

Are one factor logarithmic volatility models useful to fit the features of financial data? An application to microsoft data.

This paper provides empirical evidence that continuous time models with one factor of volatility, in some conditions, are able to fit the main characteristics of financial data. It also reports the importance of the feedback factor in capturing the strong volatility clustering of data, caused by a possible change in the pattern of volatility in the last part of the sample. We use the Efficient Method of Moments (EMM) by Gallant and Tauchen (1996) to estimate logarithmic models with one and two stochastic volatility factors (with and without feedback) and to select among them.

Convergence across countries and regions: theory and empirics

This paper surveys the recent literature on convergence across countries and regions. I discuss the main convergence and divergence mechanisms identified in the literature and develop a simple model that illustrates their implications for income dynamics. I then review the existing empirical evidence and discuss its theoretical implications. Early optimism concerning the ability of a human capital-augmented neoclassical model to explain productivity differences across economies has been questioned on the basis of more recent contributions that make use of panel data techniques and obtain theoretically implausible results. Some recent research in this area tries to reconcile these findings with sensible theoretical models by exploring the role of alternative convergence mechanisms and the possible shortcomings of panel data techniques for convergence analysis.

Likelihood-based approaches to modeling demand for medical care

We review recent likelihood-based approaches to modeling demand for medical care. A semi-nonparametric model along the lines of Cameron and Johansson's Poisson polynomial model, but using a negative binomial baseline model, is introduced. We apply these models, as well a semiparametric Poisson, hurdle semiparametric Poisson, and finite mixtures of negative binomial models to six measures of health care usage taken from the Medical Expenditure Panel survey. We conclude that most of the models lead to statistically similar results, both in terms of information criteria and conditional and unconditional prediction. This suggests that applied researchers may not need to be overly concerned with the choice of which of these models they use to analyze data on health care demand.

Sobre la fiabilidad de los datos de renta en el Panel de Hogares de la Unión Europea (PHOGUE, 1994)

Este trabajo tiene por objetivo evaluar la fiabilidad de los datos de renta procedentes de la primera Ola del PHOGUE (Panel de Hogares de la Unión Europea) de 1994, versión nacional del Production Data

Subjective income expectations, canonical models and income risk

Expectations are central to behaviour. Despite the existence of subjective expectations data, the standard approach is to ignore these, to hypothecate a model of behaviour and to infer expectations from realisations. In the context of income models, we reveal the informational gain obtained from using both a canonical model and subjective expectations data. We propose a test for this informational gain, and illustrate our approach with an application to the problem of measuring income risk.

La transmissió dels models bizantins d’Itàlia a Hispània

Estudi realitzat a partir d’una estada a Roma entre el 7 de gener i el 28 de febrer de 2006. S’ estudia la influència de les produccions bizantines i orientals a la península Ibèrica, a l’època visigoda i més enllà, fins i tot justificant una cronologia dels segles VIII-X dC per a molts dels capitells tradicionalment denominats mossàrabs del nord-oest peninsular. A més, s’enuncia una via per la investigació de les possibles influències llombardes a la península Ibèrica. També es comenten les relacions entre els capitells del nord-est peninsular i els de la Gàl.lia.

Els models d'organització metropolitana: el cas de Montreal

Estudi realitzat a partir d’una estada a l’Institut National de Recherche Scientifique, de Montreal, entre l’1 de setembre i el 30 de desembre de 2005. S’analitza el model d’organització de l’àrea metropolitana de Montreal (Canadà) després de la reforma realitzada entre 2000 i 2002, així com les causes que van conduïr a adoptar-lo.

Desenvolvimento larvário de Balanídeos em laboratório - Balanus amphitrite (Var. amphitrite)

É descrita a técnicade criação de balanus amphitrite var. amphitrite em laboratório, sob condições controladas, que permitem observações das mudas, do número de estágios e, ainda são apresentadas as características de cada estágio. Balanus amphitrite amphitrite é criado pela primeira vez em laboratório com sucesso. Dos 200 Nauplii obtidos da eclosão dos ovos das lamelas dos adultos, conseguiu-se a fixação de 120 cypris e o crescimento de 78 Balanus pelo período de três meses. A alimentação usada foi Cyclotella nana, proveniente do New York Aquarium. A fase larvária de Balanus amphitrite amphitrite consiste de seis estágios de Nauplii e um estágio de Cypris. A disposição, forma, tamanho, número de setas, sétulas e espinhos diferem entre os 6 estágios. São apresentados todos os detalhes de microanatomia de cada estágio. A setação é critério valioso para a identificação dos Nauplii e pode ser usada para separar certos estágios especiais. A duração dos seis estágios é a seguinte: o primeiro estágio leva, aproximadamente, de 15 a 20 minutos; 2º estágio de 2 até 4 dias a partir do nascimento dos Nauplii; 3º estágio vai até ao 6º dia; 4º estágio é encontrado a partir do 7º dia de eclosão; 5º estágio varia entre o 9º ao 11º dia e, finalmente, o 6º estágio até o aparecimento do Cypris que se faz no 12º dia de criação. O tempo necessário para o completo desenvolvimento larvários em laboratório estende-se de 12 até 14 dias, aproximadamente. O estudo da metamorfose do Cypris, e o crescimento dos Balanídeos foi realizado por um período de tres meses no frasco de criação.

Contribuição ao estudo dos rotíferos brasileiros: synchaeta tremula var. digitata nova variedade

Em 1968 a autora deu a primeira notícia sobre a presença do gênero Synchaeta no Brasil, assinalando a espécie S. neapolitana. Presentemente, em 1972, ela publica a primeira informação sobre a espécie S. tremula com sua nova variedade digitata, distinguível pelas seguintes características, a seguir: Trophii com uncus profundamente digitado, palmado. Esta variedade foi achada na Enseada de Inhaúma (Baía de Guanabara), em águas de regime mesohalino, e regime A-mesossapróbio de poluição orgânica. Esta publicação apresenta uma chave de espécies a fim de separar S. tremula var. digitata das outras espécies e variedades.

Estudi comparatiu dels models d’organització de les últimes sis seus olímpiques

Transcripció de la intervenció del Sr. Gabriel Colomé en el Curs Universitari sobre Olimpisme que va organitzar el Centre d'Estudis Olí­mpics (CEO-UAB) el febrer de 1992. L'autor amb aquest text es proposa dos objectius principals: d'una banda, analitzar la influència de l'entorn sociopolí­tic sobre l'estructura organitzativa del Comitè Organitzador dels Jocs; de l'altra, veure com afecta el tipus de finançament en l'estructura i la infrastructura dels mateixos Jocs, i quines diferències hi ha entre els Jocs de 1972 i els següents fins a arribar a Barcelona.

Well-posedness and invariant measures for HJM models with deterministic volatility and Lévy noise

We give sufficient conditions for existence, uniqueness and ergodicity of invariant measures for Musiela's stochastic partial differential equation with deterministic volatility and a Hilbert space valued driving Lévy noise. Conditions for the absence of arbitrage and for the existence of mild solutions are also discussed.

Estimation of dynamic latent variable models using simulated nonparametric moments

Given a model that can be simulated, conditional moments at a trial parameter value can be calculated with high accuracy by applying kernel smoothing methods to a long simulation. With such conditional moments in hand, standard method of moments techniques can be used to estimate the parameter. Since conditional moments are calculated using kernel smoothing rather than simple averaging, it is not necessary that the model be simulable subject to the conditioning information that is used to define the moment conditions. For this reason, the proposed estimator is applicable to general dynamic latent variable models. Monte Carlo results show that the estimator performs well in comparison to other estimators that have been proposed for estimation of general DLV models.

Generalized factor models: a bayesian approach

There is recent interest in the generalization of classical factor models in which the idiosyncratic factors are assumed to be orthogonal and there are identification restrictions on cross-sectional and time dimensions. In this study, we describe and implement a Bayesian approach to generalized factor models. A flexible framework is developed to determine the variations attributed to common and idiosyncratic factors. We also propose a unique methodology to select the (generalized) factor model that best fits a given set of data. Applying the proposed methodology to the simulated data and the foreign exchange rate data, we provide a comparative analysis between the classical and generalized factor models. We find that when there is a shift from classical to generalized, there are significant changes in the estimates of the structures of the covariance and correlation matrices while there are less dramatic changes in the estimates of the factor loadings and the variation attributed to common factors.

Locations and Relocations:Modelling, Determinants, and Interrelations

Empirical studies on industrial location do not typically distinguish between new and relocated establishments. This paper addresses this shortcoming using data on the frequency of these events in municipalities of the same economic-administrative region. This enables us to test not only for differences in their determinants but also for interrelations between start-ups and relocations. Estimates from count regression models for cross-section and panel data show that, although partial effects differ, common patterns arise in “institutional” and “neoclassical” explanatory factors. Also, start-ups and relocations are positive but asymmetrically related. JEL classification: C25, R30, R10. Keywords: cities, count data models, industrial location