Thesis advisor: Fabio Ghironi / Thesis advisor: Susanto Basu / The present dissertation is composed by three essays. The first essay is titled ``Comparative Advantage, Service Trade, and Global Imbalances''. The large current account deficit of the U.S. is the result of a large deficit in the goods balance and a modest surplus in the service balance. The opposite is true for Japan, Germany and China. Moreover, I document the emergence from the mid-nineties of a strong negative relation between specialization in export of services and current account balances in a large sample of OECD and developing countries. Starting from these new stylized facts, I propose in this essay a ``service hypothesis'' for global imbalances, a new explanation based on the interplay between the U.S. comparative advantage in services and the asymmetric trade liberalization process in goods trade versus service trade that took place in the last 15 years. I use a structural gravity model to quantify the extent of this asymmetry. I show that a simple two-period model can rationalize the emergence of current account deficits in the presence of such asymmetric liberalization. The key inter-temporal mechanism is the asymmetric timing of trade policies, which affects savings decisions. Finally, I explore the quantitative relevance of this explanation for global imbalances. A multi-period version of the model, fed with the asymmetric trade liberalization path found in the data, generates a current account deficit of about 1% of GDP (roughly 20% of what was observed in the U.S. in 2006). The policy implications of the analysis proposed could be relevant for the evolution of the WTO DOHA Development Round. A major focus on services, in fact, could help expanding the ``policy space'' faced by the negotiators, possibly increasing the likelihood of a successful conclusion of the round. Moreover, this paper inform also the recent debate about the need of a revaluation of the yuan. Allowing the U.S. to increase its exports of services (not necessarily to China) might help alleviating global imbalances even without movements in the exchange rates. The second essay is titled ``Estimating Trade and Investment Flows: Partners and Volumes''. I present empirical evidence from a large sample of countries for the period 2000-2006. Bilateral foreign direct investment (FDI) flows are almost never observed in the absence of bilateral trade flows, thus configuring an order of trade and investment flows. I document a similar pattern using bilateral foreign affiliate sales (FAS), aggregating them up from a large firm level dataset (ORBIS), which includes over 45,000 firms. I propose a model where heterogeneous firms face a proximity-concentration tradeoff when they decide whether to serve foreign markets through export or FDI. I derive theory-based gravity-type equations for the aggregate bilateral trade and foreign affiliate sales (FAS) flows. I then suggest a two-stage estimation procedure. In the first stage, a ordered Probit model is used to retrieve consistent estimates of the terms needed to correct the flows equations for heterogeneity and selection. In the second stage, a maximum likelihood estimator is applied to the corrected trade and FAS equations. The main results of the analysis are as follows: 1) The impact of distance, border and regional trade agreements on bilateral foreign affiliate sales becomes substantially smaller after controlling for selection and firms' heterogeneity (hence separating the impact on the extensive versus the intensive margin). 2) The same ``attenuation'' result is found also for the trade equations, consistently with HMR. 3) When FAS are observed, failing to take this into account when correcting for heterogeneity and selection in the trade equations leads to differences in the estimated coefficients. The third essay is titled ``Some Evidence on the Importance of Sticky Wages'', and is co-authored with Susanto Basu and Peter Gottshalk. Nominal wage stickiness is an important component of recent medium-scale structural macroeconomic models, but to date there has been little microeconomic evidence supporting the assumption of sluggish nominal wage adjustment. We present evidence on the frequency of nominal wage adjustment using data from the Survey of Income and Program Participation (SIPP) for the period 1996-1999. The SIPP provides high-frequency information on wages, employment and demographic characteristics for a large and representative sample of the US population. The main results of the analysis are as follows. 1) After correcting for measurement error, wages appear to be very sticky. In the average quarter, the probability that an individual will experience a nominal wage change is between 5 and 18 percent, depending on the samples and assumptions used. 2) The frequency of wage adjustment does not display significant seasonal patterns. 3) There is little heterogeneity in the frequency of wage adjustment across industries and occupations 4) The hazard of a nominal wage change first increases and then decreases, with a peak at 12 months. 5) The probability of a wage change is positively correlated with the unemployment rate and with the consumer price inflation rate. To a certain extent, the three essays presented here are self-contained and deal with three different issues regarding international economics and macroeconomics. Going to a deeper level, however, the essays are linked by a common feature: they are three examples of economic research across fields. The first essay, in fact, is an example of the growing fields at the edge between international trade and international macroeconomics. While the trade of goods and services and the dynamics of macroeconomic variables such as the current account are highly interconnected in the real world, these two fields have been characterized by a large divide in the last thirty years in the economic literature. The second essay is an example of a joint study of international trade and investment flows. Also in this case, while conceptually clearly interconnected, these topics have been usually studied separately by the economic literature. Finally, the third essay is an example of research across fields (labor economics and macroeconomics) and techniques (micro-level analysis informing macroeconomic models). In this last case, macroeconomists were interested in estimating certain wage dynamics parameters highly used in macro models. However, they were largely unaware of the fact that labor economists had the data to answer those research questions. On the other hand, the labor economists had the data, but not the questions. I hope that these essays might help increasing further the awareness that more communication between economists working in different fields can bring to valuable insights. / Thesis (PhD) — Boston College, 2011. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

L'objectif de cette thèse est de contribuer à une meilleure connaissance du marché du travail dans les économies en développement à dominante informelle. Le Mali est son cas d'étude. Dans la première partie, elle met en évidence la difficulté de comprendre le chômage au travers du statut ambigu des actifs de l'informel, oscillant entre le chômage et l'emploi. Nous y montrons que l'économie informelle exacerbe l'instabilité des frontières du chômage sans toutefois aliéner la rigidité des revenus salariaux à la baisse. A l'aide d'une courbe du salaire, nous appréhendons cette dernière et présentons ses causes. La seconde partie de la thèse pr'esente les dispositifs en matière d'emploi et montre que si, d'un côté, ils répondent pour une large part aux besoins du marché du travail et visent à corriger ses principales insuffisances - notamment en matière de financement et de formation -, de l'autre, leur mise en oeuvre se révèle profondément défaillante. Ceci explique les résultats mitigés de certaines mesures malgré plus de deux décennies d'application. Dans la troisième partie, l'attention est tournée vers l'offre de travail, à la faible connaissance de laquelle on peut attribuer une partie des échecs des dispositifs d'emploi. Nous y examinons le rôle de l'environnement familial dans la participation au marché du travail et dans la prospection d'emploi et montrons que plusieurs variables de cet espace peuvent contribuer à la formulation de meilleurs dispositifs / The aim of this thesis is to contribute to a better understanding of the labour market in informal-dominated developing economies. Mali is its study case. In the first part, it highlights the difficulty to approach unemployment through the ambiguous status of the informal workers, swinging between employment and unemployment. We show that the informal economy exacerbates the instability of the unemployment frontiers without alienating the wage stickiness, which we apprehend through a wage curve. The second part of the thesis presents the employment measures and shows that though, on one hand, they respond accurately to the labour market needs and aim to correct its shortcomings - particularly regarding the financing and training -, on the other hand, their execution is deeply dysfunctional. That explains the mitigated results of some measures, in implementation for over two decades. In the third part, the attention is turned to the labour supply, the weak knowledge of which can partially explain the failures of the employment policies. We examine the role of the household environment in the participation decision and the job search and shows that many variables of this environment can contribute to improving the measures.