Which univariate time series model predicts quicker a crisis? The Iberia case

In this paper four univariate models are fitted to monthly observations of the number of passengers in the Spanish airline IBERIA from January 1985 to October 1994. During the first part of the sample, the series shows an upward trend which has a rupture during 1990 with the slope changing to be negative. The series is also characterized by having seasonal variations. We fit a deterministic components model, the Holt-Winters algorithm, an ARIMA model and a structural time series model to the observations up to December 1992. Then we predict with each ofthe models and compare predicted with observed values. As expected, the results show that the detenninistic model is too rigid in this situation even if the within-sample fit is even better than for any of the other models considered. With respect to Holt-Winters predictions, they faH because they are not able to accornmodate outliers. Finally, ARIMA and structural models are shown to have very similar prediction performance, being flexible enough to predict reasonably well when there are changes in trend

Consumer Cooperatives: An Alternative Institutional Model for Delivery of Urban Water Supply and Sanitation Services?

This paper describes the essential characteristics of consumer cooperatives engaged in the provision of basic services and discusses their applicability as a model for water supply and sanitation service provision in urban areas. A cooperative is an autonomous association of persons united voluntarily to meet their common economic, social, and cultural needs and aspirations through a jointly-owned and democratically-controlled enterprise. The paper focuses on system-wide urban water supply cooperatives and it is thus not concerned with urban or peri-urban cooperatives that depend on either boreholes or bulk purchases of water from a utility for distribution, nor does it refer to rural water supply cooperatives that are generally small. After a general overview of cooperatives and a discussion of the main characteristics of utility cooperatives, the paper reviews the case of SAGUAPAC, a successful urban WSS cooperative in Bolivia, from which it draws some conclusions in the form of a preliminary assessment of cooperatives as a model for delivery of urban water supply and sanitation (WSS) services

Prediction with univariate time series models: The Iberia case

In this paper we model the monthly number of passengers flying with the Spanish airline IBERIA from January 1985 to December 1992 and predict future values of the series up to October 1994. This series is characterized by strong seasonal variations and by having an upward trend which has a rupture during 1990 with the slope changing to be negative. We compare observed values with predictions made by a deterministic components model, the Holt-Winters exponential smoothing filter, an ARIMA model and a structural time series model. As expected, we show that the deterministic components model is too rigid in the presence fo breaks in trends although surprisingly the within-sample fit is better than for any of the other models considered. With respect to Holt-Winters predictions, they fail because they are not able to acommodate outliers. Finally, ARIMA and structural models are shown to have very similar prediction performance, being very flexible to predict reasonably well when there are changes in trend and outliers.ARIMA models, Breaks in trends, Deterministic components, Holt-Winters algorithm, Outliers, Intervention analysis, Structural time series models, Unobserved components models.

Interjurisdictional Competition for Higher Education and Firms

In this paper we consider two regions competing for the larger part of the investment by a mobile firm whose decision is based on the quality of human capital in each region. This in turn depends on the initial skill level and the amount of higher education in the region, with a possible spillover to the other region. Therefore each region, through subsidies, tries to attract a larger part of the academic community. Moreover a central government or agency helps the poorer region by providing it with an extra budgetary allocation. The game is nested in a series of settings which are compared, especially from the point of view of their redistributive efficiency. From a policy point of view, the paper, in line with the subsidiarity principle, first provides an argument for allocating a significant amount of the competence in matters of human capital formation, to the central authorities. It also set forth difficulties which can arise from centralizing such an amount of competence and pleas for clear rules governing the federation, especially ruling out discretionary and opportunistic behaviors of public authorities. Finally, it shows the importance of the central government being correctly informed, including being allowed to gather information by itself.higher education, interjurisdictional competition, fiscal federalism, public infrastructure

The relation between the level and uncertainty of inflation

This paper focus on the problems faced in the empirical investigation of the relation between the level and volatility of inflation. Monthly inflation series seem to be affected by both the presence of outliers and conditional heteroscedasticity. First, the paper illustrates the implications that the presence of outliers and conditional heteroscedasticity have on the usual residual diagnostics. Then, estimates of the level and volatility of inflation are obtained for each of the countries of the G-7 group. Empirical evidence for the majority of the inflation series for these countries indicates both the presence of outliers and conditional heteroscedasticity, and that estimates of the latter are sensitive to the presence of outliers. Finally, the temporal dependence found in the conditional variance is enduring.Conditional Heteroscedasticity, Diagnostic, Inflation, Outlier, Stochastic Volatility.

Is there evidence of strategic corporate tax interaction among EU countries?

In this paper we empirically investigate whether EU countries set their corporate tax interdependently and, at the same time, we examine which space may be relevant in the construction of this association. Our findings indicate the presence of tax interdependency among the EU-15 in statutory and effective corporate taxes based on the tax codes. Moreover, corporate taxes in the EU-15 seem to suffer from common external shocks.Tax mimicking; tax competition; spatial panel

Corporate Taxation and the Impact of Governance, Political and Economic Factors

In this paper we first use two international data sets to investigate how governance, political and economic factors influence corporate tax rates. We show that institutional and political factors matter: good governance reduces the tax rate; a parliamentary system, especially a plurality election system, and religious or nationalist executives too, push tax rates upward. Traditional variables also matter: economic openness has a negative effect on tax rates although market size has a positive one. Though it is not robust, interaction among neighbors also plays a role. Then we turn to theory and extend a standard model of tax competition to provide a channel for the elements set forth so far to influence tax rates formation; nested in the economic theory of lobbying that exercise provides our empirical investigation with theoretical foundations.institutions and taxation, tax competition, lobbying

Approximation on Nash sets with monomial singularities

This paper is devoted to the approximation of differentiable semialgebraic functions by Nash functions. Approximation by Nash functions is known for semialgebraic functions defined on an affine Nash manifold M, and here we extend it to functions defined on Nash subsets X of M whose singularities are monomial. To that end we discuss first "finiteness" and "weak normality" for such sets X. Namely, we prove that (i) X is the union of finitely many open subsets, each Nash diffeomorphic to a finite union of coordinate linear varieties of an affine space and (ii) every function on X which is Nash on every irreducible component of X extends to a Nash function on M. Then we can obtain approximation for semialgebraic functions and even for certain semialgebraic maps on Nash sets with monomial singularities. As a nice consequence we show that m-dimensional affine Nash manifolds with divisorial corners which are class k semialgebraically diffeomorphic, for k>m^2, are also Nash diffeomorphic.Comment: 39 page