UECE - Unidade de Estudos sobre a Complexidade na Economia / UECE - Research Unit on Complexity and Economics
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- 3-step analysis of public finances sustainability : the case of the European UnionPublication . Afonso, António; Rault, ChristopheWe use a 3-step analysis to assess the sustainability of public finances in the EU27. Firstly, we perform the SURADF specific panel unit root test to investigate the mean-reverting behaviour of general government expenditure and revenue ratios. Secondly, we apply the bootstrap panel cointegration techniques that account for the time series and cross-sectional dependencies of the regression error. Thirdly, we check for a structural long-run equation between general government expenditures and revenues via SUR analysis. While results imply that public finances were not unsustainable for the EU panel, fiscal sustainability is an issue in most countries, with a below unit estimated coefficient of expenditure in the cointegration relation with revenue as the dependent variable.
- Abnormal returns before acquisition announcements : evidence from EuropePublication . Borges, Maria Rosa; Gairifo, RicardoAcquisition announcements influence the stock price of target firms, providing an opportunity for insiders to obtain significant abnormal returns. We study the presence of positive abnormal returns before the announcement date, in target firms, quoted in Euronext markets (Belgium, France, The Netherlands and Portugal) from 2001 to 2007. We investigate whether the pre-announcement run-up of prices can be explained by rumours in the media and the percentage of capital previously owned by the bidding firm, among other factors. We examine cumulative abnormal returns in an event window of 60 days prior the acquisition announcement, with the event date adjusted for the previous disclosure of news about the acquisition, in the media. We compute a run-up index, and find that there are abnormal positive returns before the announcement date, confirming previous studies. We find that a significant part of the run-up is explained by: (i) market anticipation triggered by legitimate sources of information, namely, rumours in the media about the possibility of an acquisition bid and (ii) the percentage of capital previously owned in the target firm, by the bidding firm..
- Affirmative action through minority reserves: an experimental study on school choicePublication . Klijn, Flip; Pais, Joana; Vorsatz, MarcMinority reserves are an affirmative action policy proposed by Hafalir et al. (2013) in the context of school choice. In a laboratory experiment, we find that adding minority reserves to the GS and TTC mechanisms has positive effects on stability but is quite disappointing in terms of efficiency. Also GS induces higher rates of truth-telling by minority students and thus outclasses TTC
- Agent based models and opinion dynamics as Markov chainsPublication . Banisch, Sven; Lima, Ricardo; Araújo, TanyaThis paper introduces a Markov chain approach that allows a rigorous analysis of agent based opinion dynamics as well as other related agent based models (ABM). By viewing the ABM dynamics as a micro description of the process, we show how the corresponding macro description is obtained by a projection construction. Then, well known conditions for lumpability make it possible to establish the cases where the macro model is stillMarkov. In this case we obtain a complete picture of the dynamics including the transient stage, the most interesting phase in applications. For such a purpose a crucial role is played by the type of probability distribution used to implement the stochastic part of the model which defines the updating rule and governs the dynamics. In addition, we show how restrictions in communication leading to the co–existence of different opinions follow from the emergence of new absorbing states. We describe our analysis in detail with some specific models of opinion dynamics. Generalizations concerning different opinion representations as well as opinion models with other interaction mechanisms are also discussed. We find that our method may be an attractive alternative to mean–field approaches and that this approach provides new perspectives on the modeling of opinion exchange dynamics, and more generally of other ABM.
- Agent based models and opinion dynamics as Markov chainsPublication . Banisch, Sven; Lima, Ricardo; Araújo, TanyaThis paper introduces a Markov chain approach that allows a rigorous analysis of agent based opinion dynamics as well as other related agent based models (ABM). By viewing the ABM dynamics as a micro-description of the process, we show how the corresponding macro-description is obtained by a projection construction. Then, well known conditions for lumpability make it possible to establish the cases where the macro model is still Markov. In this case we obtain a complete picture of the dynamics including the transient stage, the most interesting phase in applications. For such a purpose a crucial role is played by the type of probability distribution used to implement the stochastic part of the model which defines the updating rule and governs the dynamics. In addition, we show how restrictions in communication leading to the co-existence of different opinions correspond to the emergence of new absorbing states. We describe our analysis in detail with some specific models of opinion dynamics. Generalizations concerning different opinion representations as well as opinion models with other interaction mechanisms are also discussed. With their obvious limitations, the models do not allow for a direct generalization to more realistic cases, their treatment is only the first step in the stochastic analysis of the micro–macro link in social simulation. We find that our method may be an attractive alternative to mean-field approaches and that this approach provides new perspectives on the modeling of opinion exchange dynamics, and more generally of other ABM.
- Agglomeration and comparative advantage in vertically-related firmsPublication . Pontes, José PedroThis paper models, in game-theoretical terms, the location of two vertically-linked monopolistic firms in a spatial economy formed by a large, high labor cost country and a relatively small, low labor cost country. It is found that the decrease in transport costs shifts firms towards the low production cost country. This process takes two different forms: in labor-intensive industries it leads to spatial fragmentation; in industries with strong input-output relations, agglomerations are conserved, although they shift toward the low labor cost country.
- Agglomeration in a vertically-linked oligopolyPublication . Pontes, José PedroThis paper examines the location of three vertically-linked firms. In a spatial economy composed of two regions, a monopolist firm supplies an input to two consumer goods firms that compete in quantities. The interaction between the firms is modelled by means of a three-stage game, where the firms first select locations, then the upstream firm chooses thedelivered prices of the intermediate good, and finally the downstream firmsselect quantitiesofthe final good. It is concluded that agglomeration is more likely to occur when the ratio between the transport cost of the intermediate good and the transport cost of the final good is higher. If this proportion is low, the existence of an agglomeration varies nonmonotonically with transport costs.
- Aggregation and emergence in agent based models : a Markov chain approachPublication . Banisch, Sven; Lima, Ricardo; Araújo, TanyaWe analyse the dynamics of agent-based models (ABMs) from a Markovian perspective and derive explicit statements about the possibility of linking a microscopic agent model to the dynamical processes of microscopic observables that are useful for a precise understanding of the model dynamics. In this way the dynamics of collective variables may be studied, and a description of macro dynamics as emergent properties of micro dynamics, in particular during transient times, is possible.
- An assessment of telecommunications regulation performance in the European UnionPublication . Afonso, António; Scaglioni, CarlaWe assess the performance of National Regulatory Authorities across 16 EU countries regarding economic regulation in telecommunications sector, by constructing a so-called Composite Regulatory Performance Indicator for regulatory aspects such as effectiveness of the national regulatory system, effectiveness of the dispute settlement body, general market access conditions and application of remedies in markets for narrowband voice, mobile, broadband and business services. This composite indicator is the output measure used in the DEA non-parametric approach. The computation of efficiency scores allows to rank the NRAs and to detect some room for improvement in terms of efficiency gains for each national authority.
- An avenue for expansionary fiscal contractionsPublication . Afonso, AntónioExpansionary fiscal contractions were first illustrated by several fiscal episodes that occurred in Europe during the 1980s. This paper suggests a simple analytical textbook model that encompasses both Keynesian and non-Keynesian effects of fiscal policy. In such a context, the possibility of expansionary fiscal contractions is linked to the responsiveness of the risk premium of domestic interest rates to the budgetary position of the government and to the existence of credit-rationed consumers.