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

On permanent and breaking waves in hyperelastic rods and rings

We prove that the only global strong solution of the periodic rod equation vanishing in at least one point $(t_0,x_0)$ is the identically zero solution. Such conclusion holds provided the physical parameter $\gamma$ of the model (related to the finger deformation tensor) is outside some neighborhood of the origin and applies in particular for the Camassa--Holm equation, corresponding to $\gamma=1$. We also establish the analogue of this unique continuation result in the case of non-periodic solutions defined on the whole real line with vanishing boundary conditions at infinity. Our analysis relies on the application of new local-in-space blowup criteria and involves the computation of several best constants in convolution estimates and weighted Poincar\'e inequalities.Comment: Corrected proofs. To appear on J. Funct. Ana

Blowup issues for a class of nonlinear dispersive wave equations

In this paper we consider the nonlinear dispersive wave equation on the real line, $u_t-u_{txx}+[f(u)]_x-[f(u)]_{xxx}+\bigl[g(u)+\frac{f''(u)}{2}u_x^2\bigr]_x=0$, that for appropriate choices of the functions $f$ and $g$ includes well known models, such as Dai's equation for the study of vibrations inside elastic rods or the Camassa--Holm equation modelling water wave propagation in shallow water. We establish a local-in-space blowup criterion (i.e., a criterion involving only the properties of the data $u_0$ in a neighbourhood of a single point) simplifying and extending earlier blowup criteria for this equation. Our arguments apply both to the finite and infinite energy case, yielding the finite time blowup of strong solutions with possibly different behavior as $x\to+\infty$ and $x\to-\infty$

IMF POLICIES FOR FINANCIAL CRISES PREVENTIONS IN EMERGING MARKETS

In emerging markets, policies for preventing and managing financial crises should be understood following the standard open economy macroeconomics text treatment. This, however, will prevent us from fully comprehending how to deal with these crises. To deal with financial crises in emerging markets, this paper brings about more promising theoretical tools borrowed from the interdisciplinary field of optimal policy design. It also considers the possibility that more than one market failure may occur simultaneously. The theoretical tools discussed here should serve to improve existing prevention and management policies. Admittedly, the interdisciplinary field of optimal policy design is comparatively young, thus offering scarce empirical support for disentangling competing models. Given this inability to decide upon the best possible model, we should consider at least two constraints that policy makers will deal with in the real world of financial crises. First, given that policy makers make crucial choices between parsimonious and innovative measures, this paper recommends parsimony because of the uncertainty about the true model. Second, high political implementation costs will always be present, and these are positively correlated with supranational institutional requirements. Considering issues of both parsimony and political constraints, we argue that any attempt to internationally harmonize rules and codes must be done with caution. With this framework in mind, we review some of the recent proposals about emerging markets crisis prevention. From the point of view of emerging countries and creditor countries taken as a whole, and benevolent IFIs, we conclude that promoting GDP indexed sovereign bonds is the best available proposal for crises prevention. In this paper, we leave aside the debate of the political economy or governance reform issues of the IFIs.

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.

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.

The Elasticity of Substitution in Demand for Non-Tradable Goods in Uruguay

This paper`s main goal is to estimate the elasticity of substitution of non-tradable goods, paying special attention to empirical problems related to time-varying parameters, missing regressors and model misspecification. To that end, the paper creates a database and estimates, via three alternative methods, quarterly series of consumption and prices of tradable and non-tradable goods for Uruguay for the period 1983-2002. The econometric estimations of the parameter of interest were performed with VEC models. These estimates give a long-run elasticity of substitution of %0. 46 in the principal model and %0. 71 and %0. 75 in the two alternative models. Parametric stability tests are performed on the principal model, and the predictive ability of the model is also tested. It is concluded that, not only is the parameter of interest stable over time, but the model also has good predictive properties, even when tested in a very demanding environment: the period following Uruguay`s change of exchange rate regime in mid-2002.

Is the exchange rate politically manipulated around elections? The evidence from Uruguay

In a small open economy, the exchange rate is a key variable from the perspective of the political economy of macro policy. It is, indeed, one of the most powerful instruments that governments can use to achieve their goals. Recent theories of political macroeconomics stress that maximization of social welfare may be just one, and perhaps not the most relevant, of such goals. Others include politicians’ own permanence in power and serving the interests of specific constituencies. This paper seeks to determine the pertinence for the Uruguayan economy of the recent literature on the political economy of exchange rate management. The predictions of various theoretical models are summarized, along with the stylized facts identified in a series of recent empirical studies. After a brief discussion on the advantages of alternative specifications to test for political cycles in the exchange rate, the theoretical predictions and stylized facts are confronted with the evidence for Uruguay since 1920. The analysis shows empirical regularities consistent with political manipulation of the exchange rate around elections.political cycles, exchange rate policy, time series models.

El papel de Canarias en las relaciones económicas internacionales con África

En esta comunicación pretendemos realizar un análisis a largo plazo de las relaciones económicas entre Canarias y África, en concreto durante la etapa capitalista. Para ello, no sólo nos centraremos en los intercambios comerciales entre ambos territorios, sino también analizaremos otros ámbitos, como el papel desarrollado por las Islas como plataforma logística internacional para los agentes económicos de otros países que realizaban transacciones económicas con África, o las inversiones realizadas por la clase empresarial isleña en los países africanos

Decentralization and Fiscal Discipline in Subnational Governments:The Bailout Problem in Uruguay

This paper analyzes the reasons behind Central Government (CG) bailouts of Subnational Governments (SNGs) in the case of Uruguay. We argued that Uruguay represents a good example of the risks of fiscal decentralization, in the context of adjustment policies, and when SNGs` responsibilities and resources have not been carefully defined. We show that, in unitary countries where SNGs lack the opportunities to misbehave that they have in federal countries (e. g. , public debt issuance, international borrowing), SNG officials find ways to finance deficits through non-compliance with politically contestable obligations. In particular, SNGs in Uruguay finance their deficits by accumulating debts with other government agencies and obtaining discretionary transfers from the CG. Through statistical analyses we show that debts and deficits are mainly related to vertical fiscal imbalances and economic conditions in the SN jurisdictions. Yet, the analysis of recent bailout episodes suggests that institutions and political factors play a role (i. e. , they are important ex-post factors). This implies that bailouts have been more than simple compensations for structural imbalances, thus creating opportunities for strategic behavior on the part of SNG authorities (partly confirmed by the disparate fiscal performance of Montevideo vis-à-vis the rest of the country).