This dissertation contains three essays in international macroeconomics and financial time series forecasting. In the first essay, I show, numerically, that a two-country New-Keynesian Sticky Prices model, driven by monetary and productivity shocks, is capable of explaining the highly positive correlation across the industrialized countries' inflation even though their cross-country correlation in money growth rate is negligible. The structure of this model generates cross-country correlations of inflation, output and consumption that appear to closely correspond to the data. Additionally, this model can explain the internal correlation between inflation and output observed in the data. The second essay presents two important results. First, gains from monetary policy cooperation are different from zero when the elasticity of substitution between domestic and imported goods consumption is different from one. Second, when monetary policy is endogenous in a two-country model, the only Nash equilibria supported by this model are those that are symmetrical. That is, all exporting firms in both countries choose to price in their own currency, or all exporting firms in both countries choose to price in the importer's currency. The last essay provides both conditional and unconditional predictive ability evaluations of the aluminum futures contracts prices, by using five different econometric models, in forecasting the aluminum spot price monthly return 3, 15, and 27-months ahead for the sample period 1989.01-2010.10. From these evaluations, the best model in forecasting the aluminum spot price monthly return 3 and 15 months ahead is followed by a (VAR) model whose variables are aluminum futures contracts price, aluminum spot price and risk free interest rate, whereas for the aluminum spot price monthly return 27 months ahead is a single equation model in which the aluminum spot price today is explained by the aluminum futures price 27 months earlier. Finally, it shows that iterated multiperiod-ahead time series forecasts have a better conditional out-of-sample forecasting performance of the aluminum spot price monthly return when an estimated (VAR) model is used as a forecasting tool.

En los últimos años se ha desarollado mucho la literatura que utiliza modelos estocásticos de equilibrio económico general en economía abierta. En esta clase de modelos el primer capítulo estudia si el banco central tiene que fijarse en al inflación medida mirando al los precios al consumo (CPI) o a los precios a la producción. Se demonstra como la introducción de competencia monopolística en el mercado del trabajo y rigidez de los salarios nominales justifica el utilizo de la inflación medida sobre CPI. En el segundo capítulo el enfoque es sobre las diferentes volatilidades de la inflación entre paísos de la unión monetaria y como esto se puede relacionar con diferentes estructuras del mercado del trabajo. En el último capítulo se utiliza un modelo a dos paísos para estudiar las consecuencias de una subida del precio del petróleo sobre la inflación, los salarios reales y el producto interno bruto. / In these last years there has been an increasing literature developing DSGE Open Economy Models with market imperfections and nominal rigidities. It is the so called "New Open Economy Macroeconomics". Within this class of models the first chapter analyses the issue of whether the monetary authority should target Consumer Price Index (CPI) inflation or domestic inflation. It is shown that the introduction of monopolistic competition in the labour market and nominal wage rigidities rationalise CPI inflation targeting. In the second chapter we introduce matching and searching frictions in the labour market and relate different labour market structures across European countries with differences in the volatility of inflation across the same countries. In the last chapter we use a two-country model with oil in the production function and price and wage rigidities to relate movements in wage and price inflation, real wages and GDP growth rate to oil price changes.

Esta tesis extiende el modelo estándar Neo Keynesiano con el propósito de contestar dos preguntas: ¿cómo debe ser diseñada la política monetaria en uniones monetarias heterogéneas? y ¿cuál es el efecto de presiones competitivas sobre la dinámica de la inflación? El primer capítulo analiza el diseño de política monetaria en uniones monetarias en las cuales los países miembros muestran diferentes grados de apertura externa. Esta heterogeneidad implica que el plan de la política óptimo muestra una inclinación muy fuerte por la estabilización del tipo de cambio, con el objetivo de disminuir los diferenciales de inflación. El segundo capítulo estudia el diseño de reglas de metas en una unión monetaria con choques idiosincráticos cost-push que tienen diferentes volatilidades. El tercer capítulo estima un curva de Phillips Neo Keynesiana derivada de un modelo con entrada endógena de firmas, en el cual el número de firmas activas está inversamente relacionado con el markup deseado. Se cuantifica el efecto de las fluctuaciones del markup deseado sobre los costes marginales reales. / This thesis extends the basic New Keynesian (NK) model to answer two questions. How should monetary policy be designed in heterogeneous currency areas? What is the effect of competitive pressures on the inflation dynamics? The first chapter analyzes the monetary policy design in currency areas in which countries display different degrees of external openness. Such heterogeneity implies that the optimal policy plan exhibits a stronger motive for the currency area exchange rate stabilization in order to dampen inflation differentials. The second chapter studies the design of targeting rules in currency areas with country-specific cost-push shocks that have different volatilities. The third chapter estimates a NK Phillips curve derived from a model with endogenous firm entry in which the number of active firms is inversely related to their desired markup. It quantifies the effect of the desired markup fluctuations on the pass-through of real marginal cost. .

La thèse étudie les implications des anticipations des agents privés formées avec l’apprentissage adaptatif pour la politique monétaire optimale dans des modèles Nouveau Keynésien. Les résultats obtenus sont comparés avec la littérature adoptant l’hypothèse d’anticipations rationnelles. La banque centrale fait l’arbitrage intertemporel introduit par les anticipations à apprentissage adaptatif entre stabiliser l’inflation maintenant et dans le futur. La distorsion générée par ces anticipations rend la politique monétaire davantage agressive, même si la présence du marché financier diminue légèrement l’agressivité de la politique monétaire. Il est optimal pour le gouvernement de choisir un banquier central libéral, ce résultat peut être mitigé par un contrat d’inflation linéaire. Un autre résultat est qu’il est optimal pour la banque centrale d’être moins indépendante en termes d’instruments par rapport aux anticipations rationnelles. La possibilité de contrôle robuste de la politique monétaire est limitée par l’apprentissage adaptatif en économie fermée, et encore plus limitée en économie ouverte. Mes travaux de recherche donnent des recommandations nouvelles. / The dissertation studies the implications of private agents expectations formed with adaptive learning for the optimal monetary policy using New Keynesian models. The obtained results are compared with the literature adopting the hypothesis of rational expectations. The central bank makes the intertemporal trade-off between stabilizing current inflation or the future one that is introduced by adaptive learning expectations. The distortion which is introduced by this latter makes the monetary policy more aggressive, even if the presence of financial market slightly reduces the aggressiveness of the monetary policy. It is optimal for the government to choose a liberal central banker, but this result may be mitigated by adopting a linear inflation contract. Another result is that it is optimal for the central bank to be less instrument-independent compared to rational expectations. The possibility of robust control for monetary policy is limited by adaptive learning in a closed economy, and even more limited in an open economy. My research works give new recommendations for policy making.

[pt] Quais devem ser a características da política monetária ótima sob comprometimento em uma situação de armadilha da liquidez global quando os Bancos Centrais não coordenam suas ações? Fazendo o uso de um modelo de economia aberta com dois países, fizemos um exercício numérico para endereçar essa questão e estudar as diferenças entre este caso e uma situação cooperativa, na qual as autoridades monetárias não estão somente preocupadas com a utilidade da população nacional, mas em vez disso maximizam uma medida de bem-estar global. Nossas descobertas apontam para diferenças nas características de dependência histórica e internacional da prescrição monetária em cada um dos casos observados. Também é feita uma análise de bem-estar do nosso experimento que sugere que um Banco Central local prefere, não só permanecer restrito pelo limite inferior zero da taxa de juros nominal por um período maior, mas também que o país estrangeiro saia dessa situação o quanto antes. Por fim, fazemos uma análise de robustez dos nossos resultados variando o tamanho de cada nação e o grau de substituição dos produtos produzidos em cada localidade. / [en] What should be the characteristics of the optimal monetary policy under commitment in the situation of a global liquidity trap when Central Banks do not coordinate their actions? Using a two-country open economy model, we perform a numerical exercise in order to address this question and study the differences between this setting and a cooperative situation, when monetary authorities are not only worried with the national household utility, but instead maximize a measure of world welfare. Our findings points towards differences of history and international dependence features of optimal monetary prescriptions in each of the observed cases. We also execute a welfare analysis of our experiment that suggests that a local Central Bank prefers, not only to stay restrained by zero lower bound (ZLB) on nominal interest rates for a longer period, but also that the foreign country exists this situation as early as possible. Lastly, we make a robustness analysis of our results varying the size of each nation and the degree of substitution of the composite goods produced in each locality.

在面臨2008年金融危機後嚴峻之需求面衝擊下，多國央行紛紛調降利率，甚至調降至零利率，以期望國家能盡速脫離經濟衰退。在利率調降的過程中，由於受零利率下限的限制，單純藉由傳統貨幣政策之調控，仍可能無法使經濟從嚴峻的需求面衝擊下恢復。因此，非傳統貨幣政策也在美國、日本、英國、歐元區等國家被央行所採行做為對抗經濟衰退的政策工具。在此背景下，我們想了解如何實施最適非傳統貨幣政策。 在最適貨幣政策理論發展中，最適傳統貨幣政策發展較早，因此也較為完備。而在最適非傳統貨幣政策方面，前瞻指引(forward guidance)這項政策工具已被引入最適理論中來進行討論，但量化寬鬆(quantitative easing)直至今日還未被引入最適理論中來討論。 因此，本文建構一個封閉的新興凱因斯模型(New Keynesian)，開創性的將量化寬鬆引入最適貨幣政策理論中，來討論最適傳統與非傳統貨幣政策，也藉此與過去文獻比較施行量化寬鬆與未施行量化寬鬆之影響。 / After financial crisis occurred in 2008, countries, such as United States of America, United Kingdom, Japan and the euro area, have been mired in slow economic growth, compared with long-term, and have confronted with severe negative demand shocks which can’t be offset by zero interest-rate policy. Under the circumstance where zero lower bound was present, unconventional monetary policy was implemented by central bank of each country to end up the economic recession prospectively. As a result, we are interested in how to implement optimal unconventional monetary policy. The literatures regarding implementing conventional optimal monetary policy under demand shock were developed maturely. Forward guidance, one of unconventional monetary policy, was already developed in field of optimal monetary policy under impacted by demand shock, but quantitative easing has not been conducted in the theory of optimal monetary policy so far. Thus, we construct a close-economy by New Keynesian model to conduct quantitative easing into the theory of optimal monetary policy to discuss the optimal conventional and unconventional monetary policy, and to compare the difference corresponding to the previous literatures which without quantitative easing.

L’objet de cette thèse est de contribuer à l’analyse de l’effet des politiques visant à endiguer les risques d’instabilité financière. Les investigations menées sont d’ordre théorique (modèle DSGE) et empirique. En se plaçant dans un cadre macroéconomique d’un pays ouvert, deux dimensions doivent être prises en compte. La dimension externe est couverte par la politique de contrôles prudentiels des capitaux. De par son caractère sélectif, cette politique peut permettre de diminuer les déséquilibres externes qui ne rentrent pas dans le champ d’application macro-prudentielle. Cette dernière aborde la dimension interne et cherche à internaliser le risque global consécutif aux choix d’investissement desagents résidents. L’analyse de la coordination interne de ces deux types de mesures, macro-prudentielles et contrôles prudentiels, est essentielle pour garantir leur efficacité. En outre, les potentiels effets de débordements internationaux que peuvent entraîner les politiques de régulation prudentielle doivent être étudiés avant de valider l’utilisation de telles politiques.Voici les résultats que nous tirons de notre analyse. La politique macro-pudentielle semblent offrir de meilleurs résultats en termes de stabilité financière, des prix et de performance économique que les contrôles de capitaux. Toutefois, les contrôles prudentiels de capitaux ont leur rôle à jouer. Nos résultats montrent surtout une utilité envers la croissance excessive du crédit. L’application de contrôles prudentiels, lorsque la croissance du crédit devient excessive, peut permettre d’atténuer la surchauffe du système financier et de diminuer le décalage entre le cycle économique et financier. Par conséquent, si un choc négatif survient, les conséquences économiques devraient être amoindries. Ensuite, la politique optimale s’avère être celle combinant la politique monétaire et prudentielle, menée par une agence commune qui prend les décisions en matière de politique monétaire et prudentielle conjointement. Les politiques prudentielles s’avèrent d’autant plus nécessaires que les prêts transfrontaliers sont importants. Enfin, des effets de débordement des politiques prudentielles sur les autres pays incitent à davantage de coopération internationale ou régionale en la matière. / The aim of this thesis is to contribute to the analysis of the effect of policies aimed at curbing the risks associated with financial instability. The investigations carried out are theoretical (DSGE model) and empirical. In an open country macroeconomic framework, two dimensions must be taken into account. The external dimension is covered by the policy of prudential capital controls. Because of its selective nature, this type of policy can help reduce external imbalances that do not fall within the macroprudential scope. The latter addresses the internal dimension and seeks to internalize the overall risk resulting from the investment choices of resident agents. The analysis of the internal coordination of these two types of macro-prudential measures and prudential controls is essential to ensure their effectiveness. In addition, the potential effects of international spillovers that may result from prudential regulation policies must be studied before validating the use of such policies. We find that macroprudential policies seem to offer better results in terms of financial stability, price stability and economic performance than capital controls. However, prudential capital controls have their role to play, especially with regards to excessive credit growth. The application of prudential controls, when credit growth becomes excessive, can indeed help mitigating the overheating of the financial system and reducing the gap between economic and financial cycles. Therefore, as a negative shock occurs, its economic consequences should be lessened. Then, the optimal policy turns out to bethe one combining monetary and prudential policy, led by a joint agency that makes decisions on monetary and prudential policies. Prudential policies are all the more necessary as cross-border lending is important. Finally, the effects of prudential policies on other countries encourage more international or regional cooperation in this area.

The thesis studies three distinct issues in monetary economics using a common dynamic general equilibrium approach under the assumptions of rational expectations and nominal price rigidity. The first chapter deals with the so-called "liquidity trap" - an issue which was raised originally by Keynes in the aftermath of the Great Depression. Since the nominal interest rate cannot fall below zero, this limits the scope for expansionary monetary policy when the interest rate is near its lower bound. The chapter studies the conduct of monetary policy in such an environment in isolation from other possible stabilization tools (such as fiscal or exchange rate policy). In particular, a standard New Keynesian model economy with Calvo staggered price setting is simulated under various alternative monetary policy regimes, including optimal policy. The challenge lies in solving the (otherwise linear) stochastic sticky price model with an explicit occasionally binding non-negativity constraint on the nominal interest rate. This is achieved by parametrizing expectations and applying a global solution method known as "collocation". The results indicate that the dynamics and sometimes the unconditional means of the nominal rate, inflation and the output gap are strongly affected by uncertainty in the presence of the zero lower bound. Commitment to the optimal rule reduces unconditional welfare losses to around one-tenth of those achievable under discretionary policy, while constant price level targeting delivers losses which are only 60% larger than under the optimal rule. On the other hand, conditional on a strong deflationary shock, simple instrument rules perform substantially worse than the optimal policy even if the unconditional welfare loss from following such rules is not much affected by the zero lower bound per se. The second thesis chapter (co-authored with Andrea Pescatori) studies the implications of imperfect competition in the oil market, and in particular the existence of a welfare-relevant trade-off between inflation and output gap volatility. In the standard New Keynesian model exogenous oil shocks do not generate any such tradeoff: under a strict inflation targeting policy, the output decline is exactly equal to the efficient output contraction in response to the shock. I propose an extension of the standard model in which the existence of a dominant oil supplier (such as OPEC) leads to inefficient fluctuations in the oil price markup, reflecting a dynamic distortion of the economy's production process. As a result, in the face of oil sector shocks, stabilizing inflation does not automatically stabilize the distance of output from first-best, and monetary policymakers face a tradeoff between the two goals. The model is also a step away from discussing the effects of exogenous oil price changes and towards analyzing the implications of the underlying shocks that cause the oil price to change in the first place. This is an advantage over the existing literature, which treats the macroeconomic effects and policy implications of oil price movements as if they were independent of the underlying source of disturbance. In contrast, the analysis in this chapter shows that conditional on the source of the shock, a central bank confronted with the same oil price change may find it desirable to either raise or lower the interest rate in order to improve welfare. The third thesis chapter (co-authored with Andrea Pescatori) studies the extent to which the rise in US macroeconomic stability since the mid-1980s can be accounted for by changes in oil shocks and the oil share in GDP. This is done by estimating with Bayesian methods the model developed in the second chapter over two samples - before and after 1984 - and conducting counterfactual simulations. In doing so we nest two other popular explanations for the so-called "Great Moderation": (1) smaller (non-oil) shocks; and (2) better monetary policy. We find that the reduced oil share can account for around one third of the inflation moderation, and about 13% of the GDP growth moderation. At the same time smaller oil shocks can explain approximately 7% of GDP growth moderation and 11% of the inflation moderation. Thus, the oil share and oil shocks have played a non-trivial role in the moderation, especially of inflation, even if the bulk of the volatility reduction of output growth and inflation is attributed to smaller non-oil shocks and better monetary policy, respectively. / La tesis estudia tres problemas distintos de macroeconomía monetaria utilizando como marco común el equilibrio general dinámico bajo expectativas racionales y con rigidez nominal de los precios. El primer capítulo trata el problema de la "trampa de liquidez" - un tema planteado primero por Keynes después de la Gran Depresión de 1929. El hecho de que el tipo de interés nominal no pueda ser negativo limita la posibilidad de llevar una política monetaria expansiva cuando el tipo de interés se acerca a cero. El capítulo estudia la conducta de la política monetaria en este entorno en aislamiento de otros posibles instrumentos de estabilización (como la política fiscal o la política de tipo de cambio). En concreto, se simula un modelo estándar Neo-Keynesiano con rigidez de precios a la Calvo bajo diferentes regimenes de política monetaria, incluida la política monetaria óptima. El reto consiste en resolver el modelo estocástico bajo la restricción explícita ocasionalmente vinculante de no negatividad de los tipos de interés. La solución supone parametrizar las expectativas y utilizar el método de solución global conocido como "colocación". Los resultados indican que la dinámica y en ocasiones los valores medios del tipo de interés, la inflación y el output gap están muy influidos por la presencia de la restricción de no negatividad. El compromiso con la regla monetaria óptima reduce las pérdidas de bienestar esperadas hasta una décima parte de las pérdidas obtenidas bajo la mejor política discrecional, mientras una política de meta constante del nivel de precios resulta en pérdidas que son sólo 60% mayores de las obtenidas bajo la regla óptima. Por otro lado, condicionado a a un choque fuerte deflacionario, las reglas instrumentarias simples funcionan mucho peor que la política óptima, aun si las pérdidas no condicionales de bienestar asociadas a dichas reglas no están muy afectadas por la presencia de la restricción de no negatividad en si. El segundo capítulo de la tesis estudia las implicaciones de la competencia imperfecta en el mercado del petróleo, y en concreto la existencia de un conflicto relevante entre la volatilidad de la inflación y la del output gap de un país importador de petróleo. En el modelo estándar Neo Keynesiano, los choques petroleros exógenos no generan ningún conflicto de objetivos: bajo una política de metas de inflación estricta, la caída del output es exactamente igual a la contracción eficiente del output en respuesta al choque. Este capitulo propone una extensión del modelo básico en la cual la presencia de un proveedor de petróleo dominante (OPEP) lleva a fluctuaciones ineficientes en el margen del precio del petróleo que reflejan una distorsión dinámica en el proceso de producción de la economía. Como consecuencia, ante choques provinientes del sector de petróleo, una política de estabilidad de los precios no conlleva automáticamente a una estabilización de la distancia del output de su nivel eficiente y existe un conflicto entre los dos objetivos. El modelo se aleja de la discución los efectos de cambios exógenos en el precio del petróleo y se acerca al análisis de las implicaciones de los factores fundamentales que provocan los cambios en el precio del petróleo en primer lugar. Esto último representa una ventaja clara frente a la literatura existente, la cual trata tanto los efectos macroeconómicos como las implicaciones para la política monetaria de cambios en el precio del petróleo como si éstos fueran independientes de los factores fundamentales provocando dicho cambio. A diferencia de esta literatura, el análisis del capitulo II demuestra cómo frente al mismo cambio en el precio del petróleo, un banco central puede encontrar deseable bien subir o bajar el tipo de interés en función del origen del choque. El tercer capitulo estudia el grado en que el ascenso de la estabilidad macroeconómica en EE.UU. a partir de mediados de los 80 se puede atribuir a cambios en la naturaleza de los choques petroleros y/o el peso del petróleo en el PIB. Con este propósito se estima el modelo desarrollado en el capitulo II con métodos Bayesianos utilizando datos macroeconómicos de dos periodos - antes y después de 1984 - y se conducen simulaciones contrafactuales. Las simulaciones permiten dos explicaciones alternativas de la "Gran Moderación": (1) menores choques no petroleros; y (2) mejor política monetaria. Los resultados apuntan a que el petróleo ha jugado un papel no-trivial en la moderación. En particular, el menor peso del petroleo en el PIB a partir de 1984 ha contribuido a una tercera parte de la moderación de la inflación y un 13% de la moderación del output. Al mismo tiempo, un 7% de la moderación del PIB y 11% de la moderación de la inflación se pueden atribuir a menores choques petroleros.

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