Identifying asset price booms and busts with quantile regressions

This paper presents a methodology for detecting asset price booms and busts using non-parametric quantile regressions. The method consists in estimating the distribution of real stock prices as a function of fundamental determinants of stock returns, namely real economic activity and real interest rates. It is shown that changes in fundamentals affect not only the location but also the shape of the conditional distribution of stock prices. Asset price booms and busts are identified as realizations on the tails of that distribution. Then we use several indicators to analyse the behaviour of money and credit around the boom and bust episodes.

Identification with Averaged Data and Implications for Hedonic Regression Studies

In this estimation of models with averaged data, weighted least squares is often used and recommended as a way of improving the efficiency of the estimator. However, if the size of the different groups is not conditionally independent of the regressand, consistent estimation may not be possible at all. It is argued that in the case of some leading examples of averaged data regression, consistent estimation is possible using the usual weighted estimator.

U.S. Unemployment Duration: Has Long Become Longer or Short Become Shorter?

The U.S. labor market has been experiencing unprecedented high average unemployment duration. The shift in the unemployment duration distribution can be traced back to the early nineties. In this study, censored quantile regression methods are employed to analyze the changes in the US unemployment duration distribution. We explore the decomposition method proposed by Machado and Mata (2005) to disentangle the contribution of the changes generated by the covariate distribution and by the conditional distribution. The data used in this inquiry are taken from the nationally representative Displaced Worker Surveys of 1988 and 1998. We provide evidence that the change in the unemployment duration distribution is mainly produced by the opposing effects of a sharp rise in job-to-job transition rates and an increased sensitivity of unemployment duration to unemployment rates. Compositional changes in the labor force played a limited role. We rationalize our findings by arguing that improved screening technology is likely to be the relevant underlying mechanism at work.

Duplos (en)cena(m): ficção-crítica em Silviano Santiago

Revista Landa, v. 4, n. 1 (2015)Pretendemos, a partir do romance Mil rosas roubadas (2014) de Silviano Santiago, analisar as possibilidades de um texto autobiográfico que se faz escrita de si enquanto escrita do outro-amigo. “Realidade” e “ficção”, “verdade” e “mentira”, “ficção” e “crítica” literárias são duplos que, em deslocamento, encenam este jogo que, mediado pela(s) imagem(ns), é fingimento, erro, identificação, experiência do fora

Time series analysis for minority game simulations of financial markets

The minority game (MG) model introduced recently provides promising insights into the understanding of the evolution of prices, indices and rates in the financial markets. In this paper we perform a time series analysis of the model employing tools from statistics, dynamical systems theory and stochastic processes. Using benchmark systems and a financial index for comparison, several conclusions are obtained about the generating mechanism for this kind of evolut ion. The motion is deterministic, driven by occasional random external perturbation. When the interval between two successive perturbations is sufficiently large, one can find low dimensional chaos in this regime. However, the full motion of the MG model is found to be similar to that of the first differences of the SP500 index: stochastic, nonlinear and (unit root) stationary.Comment: LaTeX 2e (elsart), 17 pages, 3 EPS figures and 2 tables, accepted for publication in Physica

The impact of COVID 19 on waste management: Societal responses to waste during the pandemic

The COVID-19 pandemic has been having a strong impact throughout the world, changing the way we live our lives. This is due to the threat that the virus poses to human health, but also to the impact it has on waste management and consequently the environment. In this dissertation it was intended to study the way that the pandemic has been affecting waste management. With the elaboration of two interviews, it was intended to understand the role that the municipal governments of Lisbon (Portugal) and Salto (Brazil) had on waste management during the pandemic and if the management process has been adequate. It was also intended, with the elaboration of two questionnaires, to understand how the population of both these countries has been affected and which possible impacts can the citizens behavior have in this waste management process. The results showed that both these municipal governments and their respective countries are subject to factors like geographic limitations, population density and social diversity, which directly affect the process of waste management, however there are similarities in the approaches followed. It was also noted that the way to obtain positive results in this waste management process does not depend unilaterally on the intervention of the government nor the social behavior, but the cooperation between both parts. Lastly it was also noted that all the countries must invest in environmental education and conscientization, so the citizens can understand from early on, the impacts that their habits can have on the environment.A pandemia do COVID-19 tem vindo a ter um forte impacto por todo o mundo, mudando o modo como vivemos as nossas vidas. Tal deve-se à ameaça que o vírus apresenta para a saúde humana, mas também ao impacto que tem na gestão de resíduos e consequentemente no meio ambiente. Nesta dissertação procurou-se estudar os impactos que a pandemia tem vindo a ter na gestão de resíduos. Procurou-se, através de duas entrevistas elaboradas, compreender o papel que os governos municipais de Lisboa (Portugal) e Salto (Brasil) tiveram na gestão de resíduos durante a pandemia e se o processo de gestão tem sido adequado. Procurou-se ainda, através de dois questionários elaborados, compreender como a população destes dois países tem sido afetada e que possíveis impactos podem os comportamentos dos cidadãos ter neste processo de gestão de resíduos. Os resultados mostram que ambos os municípios estudados e os respetivos países estão sujeitos a fatores como limitações geográficas, densidade populacional e diversidade social, que afetam diretamente o processo de gestão de resíduos, no entanto encontram-se semelhanças nas abordagens seguidas. Notou-se ainda que o modo de obter resultados positivos no processo de gestão de resíduos não depende unilateralmente da intervenção do governo nem do comportamento social, mas sim de uma cooperação entre ambas as partes. Por fim notou-se também que todos os países devem investir em planos de educação e consciencialização ambiental, de modo a que os cidadãos compreendam desde cedo o impacto que os seus hábitos podem ter no meio ambiente