The research behind the advice
Ideas, tested.
Journal articles spanning trade policy, services, logistics, and economic modeling. Explore the findings, what they mean for policy, and the papers themselves.
42 articles
Border frictions and potential trade in the structural gravity model
Applied Economics Letters, 33(10), 1694–1698 · Online first: 2025
This article gives “potential trade” a concrete economic meaning: the trade that would occur if an exporter-specific border friction were removed. It shows how to calculate that friction and simulate the change using a structural gravity model.
The Surprising Bias of PPML Estimates of Structural Gravity Models With Two-Way Fixed Effects
Review of International Economics, 34(3), 615–631
This article examines finite-sample bias in PPML estimates of structural gravity models with exporter and importer fixed effects. It combines a theoretical characterization, simulations, and an application to observed trade data to assess when bias matters and how to reduce it.
Bias in Poisson Pseudo-Maximum Likelihood estimation of structural gravity models: how much of a problem for applied research?
Applied Economics Letters, 32(2), 222–227 · Online first: 2023
This article revisits influential simulation evidence that PPML performs poorly in structural gravity estimation. It shows how the size of the simulated bias depends on the amount of unexplained variation in trade data.
Pre-trends matter for estimating the causal effect of the WTO on bilateral trade
Applied Economics Letters · Online first: October 30, 2025
This article reassesses the trade effect of WTO membership using structural gravity and methods that allow accession effects to differ across cohorts. It examines whether countries’ trade was already evolving differently before membership.
Extending and understanding: an application of machine learning to the World Bank’s logistics performance index
International Journal of Physical Distribution & Logistics Management, 53(9), 985–1014
This article uses machine learning and widely available country data to extend the coverage of the World Bank’s Logistics Performance Index. It also identifies groups of country characteristics that help predict logistics performance.
Regional integration and services in African value chains: Retrospect and prospect
The World Economy, 46(11), 3231–3258
This article examines how services contribute to African value chains, both as exports and as inputs embodied in goods. It combines value-added accounting with simulations of regional goods-market integration.
Modelling global value chains: From trade costs to policy impacts
The World Economy, 45(8), 2478–2509 · 2022 Corden Prize
This article connects trade-policy changes to global value-chain trade through a multi-country, multi-sector model with input-output links. An application examines the contribution of improvements in trade facilitation between 2015 and 2019.
Trade, conflict and informality: Evidence from the South Sudanese civil war
The World Economy, 45(3), 867–894 · Online first: 2021
Civil conflict can disrupt neighboring economies through cross-border trade, with very different consequences for formal businesses and informal traders. This article combines Ugandan customs records with surveys of informal trade to examine the effects of the South Sudanese civil war.
Services Trade Policies and Economic Integration: New Evidence for Developing Countries
World Trade Review, 20(1), 115–134 · Online first: 2020
This article uses machine learning and regulatory information from the World Bank and WTO to extend OECD-style measures of services trade restrictiveness to 23 additional countries. The resulting Services Policy Index connects detailed policy information with observed trade patterns.
Time, uncertainty and trade flows
The World Economy, 43(9), 2375–2392
Using transaction records from international parcel deliveries, this article studies both the length and the predictability of transport times. It shows why reliable delivery matters alongside faster delivery in international trade.
What does “doing business” really measure? Evidence from trade times
Economics Letters, 192, 109215
This article examines what the Doing Business trade-time indicators actually capture. A structural gravity analysis compares their relationship with goods and services trade and contrasts them with measures of specific trade-facilitation policies.
Mega-regional trade agreements and Asia: An application of structural gravity to goods, services, and value chains
Journal of the Japanese and International Economies, 51, 32–42
This article uses structural gravity to compare the trade, welfare, and value-chain implications of alternative mega-regional integration scenarios in Asia. The simulations cover goods and services and distinguish intermediate from final products.
International input-output linkages and exogenous shock transmission: a simple model
Economics Bulletin, 38(4), 2362–2370
This article develops a simple network model of how shocks spread through international input-output links. It then examines whether network centrality helps explain country-sector output changes during the global financial crisis.
Openness and Innovation
South Asia Economic Journal, 18(1), 64–75
This paper uses Indian firm-level data to examine how exporting and importing intermediate inputs relate to innovation. It considers new products, processes, organizational systems, and the resources firms devote to research and development.
Services Productivity, Trade Policy and Manufacturing Exports
The World Economy, 40(3), 499–516
How do services shape manufacturing competitiveness? Firm-level evidence from more than 100 developing countries links services productivity and access to services inputs with manufacturers’ productivity and export performance.
Did APEC’s Trade Facilitation Action Plans deliver the goods?
Journal of Asian Economics, 43, 1–11
Did APEC meet its goal of cutting trade transaction costs by 10% over 2002–2010? This paper uses trade costs inferred from trade and production patterns to assess progress across the region and its individual economies.
Infrastructure, trade facilitation, and network connectivity in Sub-Saharan Africa
Journal of African Trade, 3(1–2), 1–22
This paper maps countries’ connections to value chains in textiles and clothing and in agriculture, with a focus on Sub-Saharan Africa. It examines how those connections relate to infrastructure and trade facilitation at home and in neighboring countries.
Measuring Connectivity in a Globally Networked Industry: The Case of Air Transport
The World Economy, 39(3), 369–385
This paper develops the Air Connectivity Index, a measure of how well countries connect to the global air transport network. It captures the strength and breadth of connections, including the role of hubs and indirect links.
Trade Costs in the Developing World: 1996–2010
World Trade Review, 15(3), 451–474
This paper develops broad measures of bilateral trade costs from trade and production data for 167 countries. It compares manufacturing and agriculture and examines how trade costs differ across income groups and regions.
US phytosanitary restrictions: the forgotten non-tariff barrier
Journal of International Trade Law and Policy, 15(1), 2–27
This study examines US plant-health restrictions on fresh fruit and vegetables. It documents how a system requiring explicit authorization for each exporting country and product can constrain market access, alongside evidence on the political economy of those decisions.
Overcoming trade logistics challenges: Asia-Pacific experiences
Asia Pacific Journal of Marketing and Logistics, 27(3), 444–466
This paper reviews logistics performance and reform experiences across the Asia-Pacific. It identifies ten policy challenges and uses case studies to connect supply-chain efficiency with inclusive development.
Product Standards and Export Diversification
Journal of Economic Integration, 30(2), 300–333
This paper examines how EU voluntary product standards affect the variety of textiles, clothing, and footwear imported from trading partners. It focuses on whether harmonization with international standards changes the market-access challenge for developing countries.
Reputation matters: Spillover effects for developing countries in the enforcement of US food safety measures
Food Policy, 55, 81–91
Using US food-import refusal data, this paper examines how compliance histories extend beyond individual products and countries. It finds evidence of reputational spillovers across related products and neighboring exporters.
Who profits from trade facilitation initiatives? Implications for African countries
Journal of African Trade, 2(1–2), 51–70
This paper asks whether trade facilitation mainly benefits large lead firms or also reaches smaller suppliers in developing countries. It combines a discussion of value-chain mechanisms with firm-level evidence on exporting and border delays.
Export and FDI premia among services firms in the developing world
Applied Economics Letters, 21(3), 176–179
This paper compares internationally engaged services firms with domestic firms using enterprise surveys from developing countries. It asks whether the export and foreign-ownership premia familiar from manufacturing also appear in services.
Facilitating international production networks: The role of trade logistics
The Journal of International Trade & Economic Development, 23(7), 979–999
This paper compares the relationship between logistics performance and trade in parts and components with the relationship for final goods. It examines production networks globally, with particular attention to the Asia-Pacific and trade among developing countries.
The Paradox of ‘Preferences’: Regional Trade Agreements and Trade Costs in Services
The World Economy, 37(12), 1751–1772
This paper studies services commitments in regional trade agreements alongside bilateral trade-cost data. It asks how much preferential agreements change services trade costs, and who benefits.
Measuring the cost of international trade in services
World Trade Review, 12(4), 719–735
How large are the costs of trading services across borders? This paper constructs a theory-based dataset using domestic production and international trade, revealing substantial barriers even between relatively integrated economies.
Product standards and developing country agricultural exports: The case of the European Union
Food Policy, 42, 1–10
The paper examines how voluntary European Union standards affect agricultural exports. It shows why standards can act as barriers in some markets and as useful market information in others.
Services Trade, Regulation and Regional Integration: Evidence from Sectoral Data
The World Economy, 36(11), 1393–1405
Using sector-level services restrictions, this paper examines how regulation and regional integration relate to cross-border trade. The results show that the relevant barriers and links between delivery modes differ markedly across services industries.
The Poisson quasi-maximum likelihood estimator: a solution to the ‘adding up’ problem in gravity models
Applied Economics Letters, 20(6), 515–519
This paper demonstrates an important accounting property of Poisson estimation in gravity models. Properly specified Poisson models preserve aggregate trade totals when fitting bilateral flows.
Trade times, importing and exporting: firm-level evidence
Applied Economics Letters, 20(9), 879–883
Firm-level data from 85 developing countries connect border delays with both access to imported inputs and export performance. The analysis also examines whether firms export directly or rely on intermediaries.
Trade costs and productivity in services sectors
Economics Letters, 114(1), 36–38
This paper connects the international costs of trading services with sectoral productivity. It extends to services the evidence that trade costs matter for how efficiently resources are used.
When are adaptive expectations rational? A generalization
Economics Letters, 115(1), 4–6
This theoretical note connects adaptive learning with rational forecasting. Allowing the learning parameter to vary over time extends adaptive expectations to a broad class of time-series models.
Air cargo transport in APEC: Regulation and effects on merchandise trade
Journal of Asian Economics, 22(3), 203–212
Air transport policy affects much more than the aviation industry. This study links the openness of bilateral aviation regimes with merchandise trade among APEC economies.
The Trade Impact of Enhanced Multimodal Connectivity in the Asia-Pacific Region
Journal of Economic Integration, 26(4), 624–650
This paper develops measures of how different transport modes work together and relates them to Asia-Pacific trade. It highlights the role of logistics capability as well as physical infrastructure.
Trade Facilitation and Export Diversification
The World Economy, 34(1), 101–122
This paper examines whether lower trading and business entry costs help developing countries export a wider range of products. Evidence from 118 countries points to trade facilitation as a practical route to diversification.
Geographical Diversification of Developing Country Exports
World Development, 38(9), 1217–1228
What helps developing countries reach more export destinations? This paper examines domestic export costs, foreign tariffs, and transport costs across 117 countries.
Help or Hindrance? The Impact of Harmonised Standards on African Exports
Journal of African Economies, 18(5), 711–744
This paper studies how European Union product standards affect African textiles and clothing exports. It distinguishes standards aligned with international norms from standards specific to the EU.
Trade facilitation in ASEAN member countries: Measuring progress and assessing priorities
Journal of Asian Economics, 20(4), 367–383
This study compares trade facilitation performance across ASEAN and assesses priorities for reform. It brings infrastructure, information technology, services, and border procedures into the same analytical framework.
Transparency and Regional Integration in the Asia Pacific
The World Economy, 32(3), 479–508
This paper measures transparency through the predictability and simplicity of the trading environment. Using APEC as a case study, it examines how these features contribute to regional integration.
Trade, Infrastructure, and Roadways in Europe and Central Asia: New Empirical Evidence
Journal of Economic Integration, 22(4), 723–747
This paper combines a detailed road network database with a gravity model to examine trade across Europe and Central Asia. It shows why infrastructure investment in a transit country can generate substantial benefits for its neighbors.