Identifying networks in social media: The case of #Grexit

We examine the intensity of ‘#Grexit’ usage in Twitter during a period of economic and financial turbulence. Using a frequency-analysis technique, we illustrate that we can extract detailed information from social media data. This allows us to map the networks of interest as it is reflected in Twitter. Our findings identify high-interest in Grexit from Twitter users in key peripheral countries, core Eurozone members as well as core EU member states outside the Eurozone. Overall, our study presents a useful tool for identifying clusters. This is part of a new research agenda utilising the information extracted from big data available via social media channels

Business Cycle Synchronization of the Visegrad Four and the European Union

In this paper, we map the process of synchronization of the Visegrad Four within the framework of the European Union using the wavelet techniques. In addition, we show that the relationship of output and key macroeconomic indicators is dynamic and varies over time and across frequencies. We study the synchronization applying the wavelet cohesion measure with time-varying weights. This novel approach allows for studying the dynamic relationship among countries from a different perspective than usual timedomain models. Analysing monthly data from 1990 to 2014, the results for the Visegrad region show an increasing co-movement with the European Union after the countries began with preparation for the accession to the European union. The participation in a currency union possibly increases the co-movement. Further, analysing the Visegrad and South European countries' synchronization with the European Union core countries, we find a high degree of synchronization in long-term horizons

On Some Problems in Discrete Wavelet Analysis of Bivariate Spectra with an Application to Business Cycle Synchronization in the Euro Zone

The paper considers some of the problems emerging from discrete wavelet analysis of popular bivariate spectral quantities like the coherence and phase spectra and the frequency-dependent time delay. The approach taken here, introduced by Whitcher and Craigmile (2004), is based on the maximal overlap discrete Hilbert wavelet transform (MODHWT). Firstly, we point at a deficiency in the implementation of the MODHWT and suggest using a modified implementation scheme resembling the one applied in the context of the dual-tree complex wavelet transform of Kingsbury (see Selesnick et al., 2005). Secondly, via a broad set of simulation experiments we examine small and large sample properties of two wavelet estimators of the scale-dependent time delay. The estimators are: the wavelet cross-correlator and the wavelet phase angle-based estimator. Our results provide some practical guidelines for empirical examination of short- and medium-term lead-lag relations for octave frequency bands. Besides, we show how the MODHWT-based wavelet quantities can serve to approximate the Fourier bivariate spectra and discuss certain issues connected with building confidence intervals for them. The discrete wavelet analysis of coherence and phase angle is illustrated with a scale-dependent examination of business cycle synchronization between 11 euro zone member countries. The study is supplemented with wavelet analysis of variance and covariance of the euro zone business cycles. The empirical examination underlines good localization properties and high computational efficiency of the wavelet transformations applied, and provides new arguments in favour of the endogeneity hypothesis of the optimum currency area criteria as well as a wavelet evidence on dating the Great Moderation in the euro zone

Novel approach to analysing large data sets of personal sun exposure measurements

Personal sun exposure measurements provide important information to guide the development of sun awareness and disease prevention campaigns. We assess the scaling properties of personal ultraviolet radiation (pUVR) sun exposure measurements using the wavelet transform (WT) spectral analysis to process long-range, high-frequency personal recordings collected by electronic UVR dosimeters designed to measure erythemal UVR exposure. We analysed the sun exposure recordings of school children, farmers, marathon runners and outdoor workers in South Africa, and construction workers and work site supervisors in New Zealand. We found scaling behaviour in all the analysed pUVR data sets. We found that the observed scaling changes from uncorrelated to long-range correlated with increasing duration of sun exposure. Peaks in the WT spectra that we found suggest the existence of characteristic times in sun exposure behaviour that were to some extent universal across our data set. Our study also showed that WT measures enable group classification, as well as distinction between individual UVR exposures, otherwise unattainable by conventional statistical methods

Output Gap Similarities in Europe: Detecting Country Groups

The literature on business cycle synchronization in Europe frequently presumes an alleged 'core-periphery' pattern without providing empirical verification of the underlying cyclical (dis)similarities or the supposed but unobservable 'European business cycle(s)'. To provide a data-based country group analysis, we apply a fuzzy clustering approach to quarterly output gap series of 27 European countries over the period 1996-2015. Our results confirm the existence of a persistent core cluster as opposed to clusters on the Eastern and Southern European peripheries, highlighting the inadequate composition of the euro area (EA). Moreover, we find that Germany's business cycle is not a suitable substitute for the core. By analyzing the relation between the identified 'European core business cycle' and the peripheral cycles over time, we show diverging patterns for the southern periphery after the financial crisis, casting doubt on the endogeneity properties of the EA

Time-Scale Analysis of Sovereign Bonds Market Co-Movement in the EU

We study co-movement of 10-year sovereign bond yields of 11 EU countries. Our analysis is focused mainly on changes of co-movement in the crisis period, especially near two significant dates - the fall of Lehman Brothers, September 15, 2008, and the announcement of increase of Greek's public deficit in October 20, 2009. We study co-movement dynamics using wavelet analysis, it allows us to observe how co-movement changes across scales, which can be interpreted as investment horizons, and through time. We divide the countries into three groups; the Core of the Eurozone, the Periphery of the Eurozone and the states outside the Eurozone. Results indicate that co-movement considerably decreased in the crisis period for all countries pairs, however there are significant differences among the groups. Furthermore, we demonstrate that co-movement of bond yields significantly varies across scales

Processos de democracia direta: sim ou não? Os argumentos clássicos à luz da teoria e da prática

Regularmente surgem controvérsias sobre os processos de democracia direta, dos quais os mecanismos mais frequentes são a iniciativa popular, o plebiscito e o referendo. Por um lado, há autores que defendem a posição de que essas instituições tornam o jogo político mais lento, caro, confuso e ilegítimo; outros defendem a posição contrária e argumentam que processos de democracia direta são fundamentais para os cidadãos e a qualidade da democracia. O presente estudo analisa esse tema em torno de sete questões, baseadas em considerações teóricas e pesquisas empíricas: 1. A questão entre o minimalismo e o maximalismo democrático; 2. A concorrência entre maioria e minoria; 3. A concorrência entre as instituições representativas e os processos de democracia direta; 4. A questão da competência dos cidadãos; 5. A questão dos efeitos colaterais dos processos de democracia direta; 6. A questão do tamanho do eleitorado; 7. A questão dos custos dos processos de democracia direta. As sete questões são analisadas a partir de uma revisão bibliográfica que considera tanto fontes nacionais como internacionais. O estudo mostra que os processos de democracia direta podem ser um complemento para as instituições representativas em um sistema democrático. O bom desempenho dos plebiscitos, referendos e iniciativas populares depende tanto da regulamentação destes como também do desempenho das outras instituições políticas e da situação socioeconômica de um país. O estudo permite ampliar e aprofundar o debate sobre processos de democracia direta no Brasil

Data on The Performance of OECD's Composite Leading Indicator

OECD data on "OECD's composite leading indicators", "Industrial Production", "Unemployment", and "Real GDP Growth" for Australia, Canada, Denmark, Finland, France, Germany, Ireland, Italy, Japan, Mexico, New Zealand, Portugal, Spain, Sweden, UK, and the US, covering the period 1991Q1 to 2019Q2.It is associated with the paper "The Performance of OECD's Composite Leading Indicator", which tests if "OECD's composite leading indicators" truly lead the mentioned business cycle indicators.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Oil shocks and the Euro as an Optimum Currency Area

SWe use wavelet analysis to study the impact of the Euro adoption on the oil price macroeconomy relation in the Euroland. We uncover evidence that the oil-macroeconomy relation changed in the past decades. We show that after the Euro adoption some countries became more similar with respect to how their macroeconomies react to oil shocks. However, we also conclude that the adoption of the common currency did not contribute to a higher degree of synchronization between Portugal, Ireland and Belgium and the rest of the countries in the Euroland. On the contrary, in these countries the macroeconomic reaction to an oil shock became more asymmetric after adopting the Euro.Fundação para a Ciência e a Tecnologia (FCT

Oil shocks and the Euro as an optimum currency area

We use wavelet analysis to study the impact of the Euro adoption on the oil price macroeconomy relation in the Euroland. We uncover evidence that the oil-macroeconomy relation changed in the past decades. We show that after the Euro adoption some countries became more similar with respect to how their macroeconomies react to oil shocks. However, we also conclude that the adoption of the common currency did not contribute to a higher degree of synchronization between Portugal, Ireland and Belgium and the rest of the countries in the Euroland. On the contrary, in these countries the macroeconomic reaction to an oil shock became more asymmetric after adopting the Euro.COMPETE; QREN; FEDER; Fundação para a Ciência e a Tecnologia (FCT