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Evidence of instability of the wealth effect in the USA is presented through the estimation of a Markov switching model of the long-run aggregate consumption function. The dating of the regimes appears to bear relation to movements in asset prices. A model-based explanation of the findings is suggested, highlighting the importance of the short-run relation between consumption, income and wealth in explaining the estimated long-run coefficients.

This study addresses some modelling questions related to the possibility of structural change in models with nonstationary variables. Focusing on cointegration issues, some methodological aspects are discussed, attempting to integrate coherently the several steps of the modelling strategy. These range from unit root to cointegration testing and to testing for instability in the cointegration vector. An empirical example with Portuguese data tries to illustrate the usefulness of this approach, where a simple money demand function is estimated using an error-correction model (ECM). If a break is explicitly allowed in the cointegration vector the forecasting performance of the ECM improves., Fundação para a Ciência e Tecnologia (FCT) -PRAXIS XXI BD/16141/98, POCTI/ECO/33778/2000, POCTI/ ECO/34755/2000

The aim of this paper is to compare the relative performance of several tests for the null hypothesis of cointegration, in terms of size and power in finite samples. This is carried out using Monte Carlo simulations for a range of plausible data-generating processes. We also analyze the impact on size and power of choosing different procedures to estimate the long run variance of the errors. We found that the parametrically adjusted test of McCabe et al. (1997) is the most well-balanced test, displaying good power and relatively few size distortions., The author wishes to thank Luis Martins, Haris Psaradakis, Ron Smith, and three anonymous referees for their valuable comments. The usual disclaimer applies. Financial support from the Sub-Programa Ciência e Tecnologia do Segundo Quadro Comunitário de Apoio, grant number PRAXIS/XXI/BD/16141/98 and from the Research Unit in Economic Policy – NIPE is gratefully acknowledged.

In this paper we propose a simple method of testing for cointegration in models that allow for multiple shifts in the long-run relationship. The procedure consists of carrying out conventional residual-based tests with standardized residuals from an appropriate Markov switching model. Our Monte Carlo results show that standard tests work well, even though their asymptotic validity can be questioned because they are not based on least-squares residuals. An empirical application to the present-value model of stock prices is also discussed., FCT -Fundação para a Ciência e a Tecnologia

In this paper we examine the properties of several cointegration tests when long run parameters are subject to multiple shifts, resorting to Monte Carlo methods. We assume that the changes in cointegration regimes are governed by a unobserved Markov chain process. This specification has the considerable advantage of allowing for an unspecified number of stochastic breaks, unlike previous works that consider a single, deterministic break. Our Monte Carlo analysis reveals that testing cointegration with the usual procedures is a quite unreliable task, since the performance of the tests is poor for a number of plausible regime shifts parameterizations.

Recent papers by Charemza and Syczewska (1998) and Carrion, Sansó and Ortuño (2001) focused on the joint use of unit root and stationarity tests. In this paper, the discussion is extended to the case of cointegration. Critical values for testing the joint confirmation hypothesis of no cointegration are computed and a small Monte Carlo experiment evaluates the relative performance of this procedure.

In this paper, we propose a simple method for testing cointegration in models that allow for multiple shifts in the long run relationship. The procedure consists of computing conventional residual-based tests with standardized residuals from Markov switching estimation. No new critical values are needed. An empirical application to the present value model of stock prices is presented, complemented by a small Monte Carlo experiment.

In this paper, we propose a simple method for testing cointegration in models that allow for multiple shifts in the long run relationship. The procedure consists of computing conventional residual-based tests with standardized residuals from Markov switching estimation. No new critical values are needed. An empirical application to the present value model of stock prices is presented, complemented by a small Monte Carlo experiment.

In this paper we examine, by means of Monte Carlo simulation, the properties of several cointegration tests when long run parameters are subject to structural changes. We allow for different types of stochastic and deterministic regime shifts, more specifically, changes governed by Markov chains, martingale parameter variation, sudden multiple breaks and gradual changes. Our Monte Carlo analysis reveals that tests with cointegration as the null hypothesis perform badly, while tests with the null of no cointegration retain much of their usefulness in this context.

The purchasing power parity (PPP) hypothesis is examined by means of residual-based cointegration tests. A generalized concept of cointegration is used. that is, fractional cointegration. This method aims to be a complement of the Engle-Granger procedure, whose test for cointegration assumes that the equilibrium error is strictly I(1) (nonstationary) or I(0) (stationary). It is known and it will be shown in this work through Monte Carlo simulation, that the unit root tests turn out to perform poorly against long memory alternatives. To perform a test for fractional cointegration, empirical distributions are obtained through a Monte Carlo experiment. This means that the PPP hypothesis is not con…ned to the value of the fractional estimate. By allowing equilibrium errors to follow a fractional integrated process, the fractional cointegration analysis capture a wider range of stationary and level reversion behaviour. This ‡exibility is important to a proper evaluation of the exchange rate dynamics. Two bilateral relations are studied, between Portugal as the home country and the United Kingdom and the United States of America. We also consider the use of structural change tests, since a long range of time is covered by the data, with periods that were a¤ected by di¤erent policy regimes in these countries. For this century, the empirical results provide some support for the PPP between Portugal and the two other countries. Deviations from equilibrium can be modelled by a level-reverting fractionally integrated process. Although short run deviations can occur, the results support the PPP as a long run phenomenon., Centro de Estudos de Economia e Gestão da Universidade do Minho.

In order to determine the effect of antibiotics on the course of cholera, precise observations of clinical symptoms and quantitative examination of vibrios in the stool were carried out on 17 patients with cholera El Tor from the Philippines. Seven patients were treated orally with kanamycin, tetracycline, chloramphenicol or erythromycin, 7 intravenously with chloramphenicol or tetracycline, and 3 were not given any antibiotic.Both the oral and the intravenous routes of administration of the antibiotics were suitable for shortening the period of diarrhoea and reducing the excretion of vibrios in the stool.The number of vibrios in 1 ml of watery stool during the first day of illness was about 10(8) in every case. There was marked reduction in the number within 1 hour, and complete disappearance of vibrios within 10 hours, of the start of treatment in most cases. However, vibrios reappeared later in some cases.Kanamycin, a non-absorbable antibiotic, was found to be less effective than adsorbable antibiotics such as chloramphenicol and tetracycline.

En los momentos actuales las exigencias de la Enseñanza General Básica nos plantean la necesidad, más que nunca si cabe. de un conocimiento de la realidad objetiva del alumno, y ello la de una exploración apropiada de sus aptitudes, posibilidades y límites, a fin de diagnosticar la singularidad personal del mismo, todo ello en función de un pronóstico encaminado a hacer congruentes en la enseñanza objetivo, niveles y medios. La recomendación del uso de instrumentos de exploración del nivel de inteligencia, nos hace preguntarnos por la existencia al alcance de los educadores de tales instrumentos, que siendo eficaces en sus fines sirvan a las exigencias escolares. El test Otis, pensamos puede ser el instrumento que venga a cubrir la necesidad señalada, pero tememos pueda ser siempre bien utilizado y reúna o se conozcan todas las características que son necesarias en un instrumento destinado a tal fin. Comprobar si reúne las características necesarias para poder ser utilizado con rigor científico en nuestros centros escolares, poner al alcance de quienes vayan a utilizar el test las experiencías y estudios que haya sobre el mismo, y determinar si sería viable una mejor adaptación del mismo a las exigencias actuales, es lo que nos proponemos llevar a cabo en el presente estudio, recopilando para ello cuantos datos haya en los estudios realizados sobre el test, y realizando al propio tiempo un nuevo estudio interno, serio y minucioso del mismo.

This comprehensive Handbook presents the current state of art in the theory and methodology of macroeconomic data analysis. It is intended as a reference for graduate students and researchers interested in exploring new methodologies, but can also be employed as a graduate text. The Handbook concentrates on the most important issues, models and techniques for research in macroeconomics, and highlights the core methodologies and their empirical application in an accessible manner. Each chapter is largely self-contained, whilst the comprehensive introduction provides an overview of the key statistical concepts and methods. All of the chapters include the essential references for each topic and provide a sound guide for further reading.

The interplay between order and disorder in photonic lattices opens up a wide range of novel optical scattering mechanisms, cavity-mode resonances, and applications that can be obscured by typical ordered design approaches to photonics. Striking examples include Anderson localization, random lasers, and visible light scattering in biophotonic structures such as butterfly wings. In this work, we present a profound example of light localization in photonic crystal waveguides by introducing long-range correlated disorder. Using a rigorous three-dimensional Bloch mode expansion technique, we demonstrate how interhole correlations have a negative contribution to the total out-of-plane radiative losses, leading to a pronounced enhancement of the quality factor, Q, and Q/V cavity figures of merit in the long-range correlation regime. Subsequently, the intensity fluctuations of the system are shown to globally increase with the correlation length, highlighting the nontrivial role of long-range disorder on the underlying scattering mechanisms. We also explore the possibility of creating ultrahigh quality cavity modes via interhole correlations, which have various functionalities in chip-based nonlinear optics and waveguide cavity-quantum electrodynamics.

This comprehensive Handbook presents the current state of art in the theory and methodology of macroeconomic data analysis. It is intended as a reference for graduate students and researchers interested in exploring new methodologies, but can also be employed as a graduate text. The Handbook concentrates on the most important issues, models and techniques for research in macroeconomics, and highlights the core methodologies and their empirical application in an accessible manner. Each chapter is largely self-contained, whilst the comprehensive introduction provides an overview of the key statistical concepts and methods. All of the chapters include the essential references for each topic and provide a sound guide for further reading.