DM - Documentos de trabalho / Working Papers
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- Identifying common spectral and asymmetric features in stock returnsPublication . Caiado, Jorge; Crato, NunoThis paper proposes spectral and asymmetric-volatility based methods for cluster analysis of stock returns. Using the information about both the periodogram of the squared returns and the estimated parameters in the TARCH equation, we compute a distance matrix for the stock returns. Clusters are formed by looking to the hierarchical structure tree (or dendrogram) and the computed principal coordinates. We employ these techniques to investigate the similarities and dissimilarities between the "blue-chip" stocks used to compute the Dow Jones Industrial Average (DJIA) index. For reference, we investigate also the similarities among stock returns by mean and squared correlation methods.
- Comparison of time series with unequal lengthPublication . Caiado, Jorge; Crato, Nuno; Peña, DanielThe comparison and classification of time series is an important issue in practical time series analysis. For these purposes, various methods have been proposed in the literature, but all have shortcomings, especially when the observed time series have different sample sizes. In this paper, we propose spectral domain methods for handling time series of unequal length. The methods make the spectral estimates comparable, by producing statistics at the same frequency. A first sensible approach may consist on zero-padding the shorter time series in order to increase the corresponding number of periodogram ordinates. We show that this works well provided the sample sizes are not very different, but does not give good results in case the time series lengths are very unbalanced. For this latter case, we study some periodogram-based comparison methods and construct a test. Both the methods and the test display reasonable properties for series of any lengths. Additionally and for reference, we develop a parametric comparison method. The procedures are assessed by a Monte Carlo simulation study. As an illustrative example, a periodogram method is used to compare and cluster industrial production series of some developed countries.
- A GARCH-based method for clustering of financial time series: International stock markets evidencePublication . Caiado, Jorge; Crato, NunoIn this paper, we introduce a volatility-based method for clustering analysis of financial time series. Using the generalized autoregressive conditional heteroskedasticity (GARCH) models we estimate the distances between the stock return volatilities. The proposed method uses the volatility behavior of the time series and solves the problem of different lengths. As an illustrative example, we investigate the similarities among major international stock markets using daily return series with different sample sizes from 1966 to 2006. From cluster analysis, most European markets countries, United States and Canada appear close together, and most Asian/Pacific markets and the South/Middle American markets appear in a distinct cluster. After the terrorist attack on September 11, 2001, the European stock markets have become more homogenous, and North American markets, Japan and Australia seem to come closer.
- Identification with averaged data and implications for hedonic regression studiesPublication . Silva, João Santos; Machado, JoséIn the estimation of models with averaged data, weighted least squares is often used and recommended as a way of improving the e¢ciency of the estimator. However, if the size of the di¤erent 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.
- On the Fisher-Konieczny index of price changes synchronizationPublication . Dias, D. A.; Marques, C. Robalo; Neves, P. D.; Silva, J. M. C. SantosThis note provides a structural interpretation for the index of price changes synchronization proposed by Fisher and Konieczny (2000, Economics Letters, 68, 271-277) and shows that it can be used to test the hypothesis of uniform staggering
- Time-varying fiscal policy in the U.S.Publication . Pereira, Manuel Coutinho; Lopes, Artur SilvaTo investigate time heterogeneity in the e¤ects of fiscal policy in theU.S., we use a non-recursive, Blanchard and Perotti-like structural VAR with time-varying parameters, estimated through Bayesian simulation over the 1965:2-2009:2 period. Our evidence suggests that fiscal policy has lost some capacity to stimulate output but that this trend is more pronounced for taxes net of transfers than for government expenditure, whose e¤ectiveness declines only slightly. Fiscal multipliers keep conventional signs throughout. An investigation of changes in fiscal policy conduct indicates an increase in the countercyclical activism of net taxes over time, which appears to have reached a maximum during the 2008-09 recession.
- Cohesion within the euro area and the U. S: a wavelet-based viewPublication . Lopes, Artur Silva; Rua, AntónioThe assessment of synchronization of macroeconomic fluctuations across countries or regions has been crucial, for example, for the debate on economic integration. In this paper, we propose a multivariate measure of synchronization to assess cohesion across countries or regions by resorting to wavelet analysis. This wavelet-based measure of cohesion allows one to assess how synchronization has evolved over time and across frequencies simultaneously. In particular, we investigate the cohesion among euro area countries and the cohesion within the U.S. both at the regional and state levels over the last decades. In addition, an analysis at the sectoral level is also conducted. The results obtained unveil a noteworthy heterogeneity and highlight the usefulness of a wavelet-based measure of cohesion.
- Cohesion within the euro area and the U. S: a wavelet-based viewPublication . Lopes, Artur Silva; Rua, AntónioThe assessment of synchronization of macroeconomic fluctuations across countries or regions has been crucial, for example, for the debate on economic integration. In this paper, we propose a multivariate measure of synchronization to assess cohesion across countries or regions by resorting to wavelet analysis. This wavelet-based measure of cohesion allows one to assess how synchronization has evolved over time and across frequencies simultaneously. In particular, we investigate the cohesion among euro area countries and the cohesion within the U.S. both at the regional and state levels over the last decades. In addition, an analysis at the sectoral level is also conducted. The results obtained unveil a noteworthy heterogeneity and highlight the usefulness of a wavelet-based measure of cohesion.
- Hedonic prices indexes for new passenger cars in Portugal (1997-2001)Publication . Reis, Hugo J.; Silva, J. M. C. SantosIn this paper we study the e¤ects of quality change on the price index for new passenger cars in Portugal for the years 1997-2001. Hedonic regression models are studied, giving particular emphasis to the relation between the form of the price index and the speci¤cation of the hedonic equation and estimation method used. The results indicate that the CPI component corresponding to this item may have been overestimated by as much as 2:2 percentage points per year. This corresponds to an overestimation of the overall CPI by about 0:15 percentage points per year. As a by-product of this analysis it is also possible to conclude that the quality of new cars sold in Portugal increased on average 4:8 percent per year during this period.
- Time or state dependent price setting rules? Evidence from portuguese micro dataPublication . Marques, Carlos R.; Dias, Daniel; Silva, João SantosIn this paper we analyse the ability of time and state dependent price setting rules to explain durations of price spells or the probability of changing prices.Our results suggest that simple time dependent models cannot be seen as providing a reasonable approximation to the data and that state dependent models are required to fully characterise the price setting behaviour of Portuguese firms. Inflation, the level of economic activity and the magnitude of the last price change emerge as relevant variables a.ecting the probability of changing prices. Moreover, it is seen that the impact differs for negative and positive values of these covariates.
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