Portuguese Economic Journal, 2012, Volume 11, Nº 2
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- Asymmetry, realised volatility and stock return risk estimatesPublication . Grané, Aurea; Veiga, HelenaIn this paper we estimate minimum capital risk requirements for short and long positions with three investment horizons, using the traditional GARCH model and two other GARCH-type models that incorporate the possibility of asymmetric responses of volatility to price changes. We also address the problem of the extremely high estimated persistence of the GARCH model to generate observed volatility patterns by including realised volatility as an explanatory variable into the model’s variance equation. The results suggest that the inclusion of realised volatility improves the GARCH forecastability as well as its ability to calculate accurate minimum capital risk requirements and makes it quite competitive when compared with asymmetric conditional heteroscedastic models such as the GJR and the EGARCH.
- Equilibrium existence in infinite horizon economiesPublication . Moreno-García, Emma; Torres-Martínez, Juan PabloIn sequential economies with finite or infinite-lived real assets in positive net supply, we introduce constraints on the amount of borrowing in terms of the market value of physical endowments. We show that, when utility functions are either unbounded and separable in states of nature or separable in commodities, these borrowing constraints not only preclude Ponzi schemes but also induce endogenous Radner bounds on short-sales. Therefore, we obtain existence of equilibrium. Moreover, equilibrium also exists when both assets are numéraire and utility functions are quasilinear in the commodity used as numéraire.
- Social security and economic performance in Portugal : after all that has been said and done how much has actually changed?Publication . Pereira, Alfredo M.; Andraz, Jorge M.This paper provides an empirical estimate of the macroeconomic effects of the Portuguese pay-as-you-go social security system based on data for the period 1970–2007 and on VAR estimates using GDP, the unit cost of labor, the unemployment rate, the savings rate and social security spending. The major findings are twofold. First, growing social security spending has had detrimental effects on all of the private sector variables under consideration suggesting the existence of sizable inefficiencies. Second, these inefficiencies persist despite the successive reforms that took place over the last two decades. These results highlight the need for structural reforms of the pay-as-you-go system thereby addressing the sources of these inefficiencies, regardless of whether or not the system is financially sustainable. Furthermore, any reforms designed to address sustainability concerns cannot ignore these inefficiencies or risk making them even worse and thereby hindering the quest for sustain- ability itself.
- The transition of people’s preferences for the intervention of the government in the economy of re-unified GermanyPublication . Migheli, MatteoCovering the first fifteen years immediately after German re- unification, this paper analyzes the people’s support to the transition. The focus is on individuals’ preferences for the intervention of the government in the economy and on the opinion about competition per se. Eastern German data are compared with Western German data. Using suitable data that allow for interpersonal comparisons, the paper shows that Eastern Germans have always preferred an intervention of the public hand in the economy deeper than Western Germans; these different positions have hardly converged during the examined period of time. However there are no significant differences with respect to how Germans perceive competition per se: it is considered as a good by the people living in both parts of the country.