Philippe Martin

Bio: Philippe Martin is an academic researcher from Sciences Po. The author has contributed to research in topics: Productivity & Public policy. The author has an hindex of 46, co-authored 178 publications receiving 10877 citations. Previous affiliations of Philippe Martin include Lille University of Science and Technology & Economic Policy Institute.

Economic Geography and Public Policy

Abstract: Research on the spatial aspects of economic activity has flourished over the past decade due to the emergence of new theory, new data, and an intense interest on the part of policymakers, especially in Europe but increasingly in North America and elsewhere as well. However, these efforts - collectively known as the "new economic geography" - have devoted little attention to the policy implications of the new theory. "Economic Geography and Public Policy" fills the gap by illustrating many new policy insights economic geography models can offer to the realm of theoretical policy analysis. Focusing primarily on trade policy, tax policy, and regional policy, Richard Baldwin and coauthors show how these models can be used to make sense of real-world situations. The book not only provides much fresh analysis but also synthesizes insights from the existing literature. The authors begin by presenting and analyzing the widest range of new economic geography models to date. From there, they proceed to examine previously unaddressed welfare and policy issues including, in separate sections, trade policy (unilateral, reciprocal, and preferential), tax policy (agglomeration with taxes and public goods, tax competition and agglomeration), and regional policy (infrastructure policies and the political economy of regional subsidies). A well-organized, engaging narrative that progresses smoothly from fundamentals to more complex material, "Economic Geography and Public Policy" is essential reading for graduate students, researchers, and policymakers seeking new approaches to spatial policy issues.

Industrial Location and Public Infrastructure

Abstract: This paper examines the impact of public infrastructure on industrial location when increasing returns are present. Poor infrastructure implies costs of Samuelson's `iceberg' form and alter trade both within and between countries. Trade integration implies that firms tend to locate in countries with better infrastructure so that regional policies that affect the level of public infrastructure influence economic geography. The effectiveness of such policies decreases when infrastructure improves, however, because a high level of infrastructure and strong economies of scale magnify the concentration effects of differentials in infrastructure, market size and capital-labour ratios. Infrastructure policies that facilitate intra-regional trade in the poor country lead to regional convergence but policies that facilitate intra-regional trade lead to regional divergence. We also analyse the incentives for countries to inhibit industrial relocation.

How do Different Exporters React to Exchange Rate Changes

Abstract: This paper analyzes the heterogenous reaction of exporters to exchange rate changes using a very rich French rm-level dataset with destination-specic export values and volumes on the period 19952005. We nd that high-performance rms react to a depreciation by increasing signicantly more their markup and by increasing less their export volume. This heterogeneity in pricing to market is robust to dierent measures of performance, samples and econometric specications. It is consistent with models where demand elasticity decreases with rm performance. Since aggregate exports are concentrated on high productivity rms, precisely those that absorb more exchange rate movements in

Growth and Agglomeration

Abstract: This article presents a model in which growth and geographic agglomeration of economic activities are mutually self-reinforcing processes. Economic agglomeration in one region spurs growth because it reduces the cost of innovation in that region through a pecuniary externality due to transaction costs. Growth fosters agglomeration because, as the sector at the origin of innovation expands, new firms tend to locate close to this sector. Agglomeration implies that all innovation and most production activities take place in the core region. However, as new firms are continuously created in the core, some relocate their production to the periphery.

Robust Inference with Multi-way Clustering

Abstract: In this article we propose a variance estimator for the OLS estimator as well as for nonlinear estimators such as logit, probit, and GMM. This variance estimator enables cluster-robust inference when there is two-way or multiway clustering that is nonnested. The variance estimator extends the standard cluster-robust variance estimator or sandwich estimator for one-way clustering (e.g., Liang and Zeger 1986; Arellano 1987) and relies on similar relatively weak distributional assumptions. Our method is easily implemented in statistical packages, such as Stata and SAS, that already offer cluster-robust standard errors when there is one-way clustering. The method is demonstrated by a Monte Carlo analysis for a two-way random effects model; a Monte Carlo analysis of a placebo law that extends the state–year effects example of Bertrand, Duflo, and Mullainathan (2004) to two dimensions; and by application to studies in the empirical literature where two-way clustering is present.

Micro-Foundations of Urban Agglomeration Economies

Abstract: This handbook chapter studies the theoretical micro-foundations of urban agglomeration economies. We distinguish three types of micro-foundations, based on sharing, matching, and learning mechanisms. For each of these three categories, we develop one or more core models in detail and discuss the literature in relation to those models. This allows us to give a precise characterisation of some of the main theoretical underpinnings of urban agglomeration economies, to discuss modelling issues that arise when working with these tools, and to compare different sources of agglomeration economies in terms of the aggregate urban outcomes they produce as well as in terms of their normative implications.

Market Size, Trade, and Productivity

Abstract: We develop a monopolistically competitive model of trade with firm heterogeneity—in terms of productivity differences—and endogenous differences in the “toughness” of competition across markets—in terms of the number and average productivity of competing firms. We analyse how these features vary across markets of different size that are not perfectly integrated through trade; we then study the effects of different trade liberalization policies. In our model, market size and trade affect the toughness of competition, which then feeds back into the selection of heterogeneous producers and exporters in that market. Aggregate productivity and average mark-ups thus respond to both the size of a market and the extent of its integration through trade (larger, more integrated markets exhibit higher productivity and lower mark-ups). Our model remains highly tractable, even when extended to a general framework with multiple asymmetric countries integrated to different extents through asymmetric trade costs. We believe this provides a useful modelling framework that is particularly well suited to the analysis of trade and regional integration policy scenarios in an environment with heterogeneous firms and endogenous mark-ups.

Gravity Equations: Workhorse,Toolkit, and Cookbook

Abstract: This chapter focuses on the estimation and interpretation of gravity equations for bilateral trade. This necessarily involves a careful consideration of the theoretical underpinnings since it has become clear that naive approaches to estimation lead to biased and frequently misinterpreted results. There are now several theory-consistent estimation methods and we argue against sole reliance on any one method and instead advocate a toolkit approach. One estimator may be preferred for certain types of data or research questions but more often the methods should be used in concert to establish robustness. In recent years, estimation has become just a first step before a deeper analysis of the implications of the results, notably in terms of welfare. We try to facilitate diffusion of best-practice methods by illustrating their application in a step-by-step cookbook mode of exposition.