Person:
Pierola Castro, Martha Denisse
Author Name Variants
Fields of Specialization
International economics,
Export development,
Firm-level analysis of trade
Degrees
External Links
Departments
Trade and Integration Team, Development Research Group, The World Bank
Externally Hosted Work
Contact Information
Last updated
January 31, 2023
Biography
Martha Denisse Pierola is an Economist in the Trade and International Integration Unit of the Development Research Group of the World Bank. She has published several papers on export growth and exporter dynamics and co-created the Exporter Dynamics Database –the first-ever global database on exporter growth and dynamics, based on firm-level export data. Her research studies the role of large exporters in driving trade patterns and export growth; and examines how exporter behavior varies with the stage of development. She was the leader of the team conducting the World Bank study on trade, competitiveness and regional integration in Zimbabwe. She has worked on issues related to regionalism, trade costs and trade and productivity. Before joining the World Bank, she worked as an economist for the Peruvian Government (INDECOPI) and also consulted for the private sector and other international organizations. She has a PhD in economics from the Graduate Institute of International Studies in Geneva, Switzerland and a Master of International Law and Economics from the World Trade Institute in Bern, Switzerland.
Publication Search Results
1 - 6 of 6
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Publication
Exporter Behavior, Country Size and Stage of Development: Evidence from the Exporter Dynamics Database
(World Bank, Washington, DC, 2015-10)This paper presents new data on the micro structure of the export sector for 45 countries and studies how exporter behavior varies with country size and stage of development. Larger countries and more developed countries have more exporters, larger exporters, and a greater share of exports controlled by the top 5 percent. The extensive margin (more firms) plays a greater role than the intensive margin (average size) in supporting exports of larger countries. In contrast, the intensive margin is relatively more important in explaining the exports of richer countries. Exporter entry and exit rates are higher and entrant survival is lower at an early stage of development. The paper discusses the results in light of trade theories with heterogeneous firms and the empirical literature on resource allocation, firm size, and development. An implication from the findings is that developing countries export less because the top of the firm-size distribution is truncated. -
Publication
Trade in Zimbabwe: Changing Incentives to Enhance Competitiveness
(Washington, DC: World Bank, 2015-05-22)In Zimbabwe trade has been a driver of economic growth, rising incomes, and progressive empowerment of Zimbabweans through rising standards of living and the promise of better jobs. Since 1980, through good years and bad years, increases in exports have been positively associated with increases in national income. Zimbabwe's location and resource base, together with a low-cost but relatively well educated labor force, have endowed it with a naturally high trade ratio built on a diversified base that facilitates using trade as an engine of growth. While trade volumes have rebounded smartly from the deep recession of 2007-2008, these do not offset other worrisome longer-term trends: 1) export growth during the last decade has been lackluster and failed to drive high growth; 2) agricultural exports, other than tobacco, have lost their once dominant role in the region, and are no longer a source of diversification; 3) manufacturing has withered in a continuing secular decline; and 4) Zimbabwe's export basket has become less diversified and more dependent on a narrow range of mineral and, to a lesser extent, agricultural products. In short, exports have become less diversified, less-technologically sophisticated, and less labor-intensive, and ever more dependent on a few large mining activities to provide foreign exchange and employment. This report traces the roots of this poor performance to several policy issues: poor predictability of macroeconomic policy and economic governance has created an unfavorable climate for private investment and trade; a tariff structure that dampens export profitability; industrial policies (indigenization policy in particular) that undermine investor confidence and inhibits private investment; and finally, competition-limiting policies toward services that limit connectivity of Zimbabweans and raise trade costs. The good news arising from the study is that the remedies for these policy shortcomings lie in Zimbabwean hands. If the government were to adopt reforms that reconfigure economy-wide incentives and trade and industrial policies, it could promote sustained growth, economic diversification and empowerment of poor people. -
Publication
The Role of Imports for Exporter Performance in Peru
(World Bank, Washington, DC, 2015-11)Using highly disaggregated firm-level customs transaction data for imports and exports in Peru over the 2000–2012 period, this paper explores the relationship between imports of intermediate inputs and firm export performance. The paper shows that greater use, variety, and quality of imported intermediate inputs is significantly correlated with higher exports, faster export growth, greater diversification of export markets, and higher quality exports (as measured by relative unit prices) at the firm level. This relationship is robust and persistent to controls for unobserved firm heterogeneity and year fixed effects. The use of imported inputs is also associated with higher productivity at the firm level. Considering the relationship between specific trade policy measures and the import performance of those exporters that are direct importers, the analysis shows that those exposed to higher tariffs and nontariff measures import less in total and exhibit lower import variety. The use of the advanced clearance procedure as the modality to clear customs for imports is favorable to the import performance of exporter-importers, in that the users of the modality import more and import a more diversified bundle of inputs than those that do not use it, even after controlling for firm size. -
Publication
Export Competitiveness: Why Domestic Market Competition Matters
(World Bank, Washington, DC, 2015-06)This review of the empirical literature shows that industries with more intense domestic competition will export more. Competition law enforcement can be traced to export performance and is complementary to trade reforms. Pro-competition market regulation that reduces restrictions and promotes competition, where it is viable, is an important determinant for trade. The elimination of barriers to entry and rivalry, and a level playing field in upstream sectors contributes to export competitiveness in downstream manufacturing sectors. In some sectors, effective competition policy can directly lower trade costs. -
Publication
The Intensive Margin in Trade
(World Bank, Washington, DC, 2018-10)Is the variation in bilateral trade flows across countries primarily due to differences in the number of exporting firms (the extensive margin) or in the average size of an exporter (the intensive margin)? And how does this affect the estimation and quantitative implications of the Melitz (2003) trade model? The benchmark Melitz model with Pareto-distributed firm productivity and fixed costs of exporting, predicts that, conditional on the fixed costs of exporting, all variation in exports across trading partners should occur on the extensive margin. This paper subjects this theoretical prediction to a reality check drawing upon the World Bank's Exporter Dynamics Database (EDD) which has firm-level exports from 50 developing countries to all destinations. Around 50 percent of the variation in exports across trading partners is shown to be along the intensive margin, contradicting the benchmark Melitz-Pareto model. The paper finds that moving from a Pareto to a lognormal distribution of firm productivity allows the Melitz model to successfully match the role of the intensive margin evident in the EDD. The paper then studies the implications of our findings for quantitative trade theory. Using likelihood methods and the EDD, a generalized Melitz model with a joint lognormal distribution for firm productivity, fixed costs and demand shifters is estimated, and exact hat algebra is used to quantify the counterfactual effects of a decline in trade costs on trade flows and welfare in the estimated model. Finally, these effects are compared to those that would be predicted by the Melitz-Pareto model, with the Pareto shape parameter chosen to match the average trade elasticity implied by the estimated Melitz-lognormal model. The paper shows that the effects on welfare turn out to be quite close to those in the standard Melitz-Pareto model even though the effects on trade flows remain different. -
Publication
The Origins and Dynamics of Export Superstars
(Published by Oxford University Press on behalf of the World Bank, 2020-02)Export superstars are important for export growth and diversification and are typically born large. Firm-level data on manufacturing trade from 32 developing countries show that the top five exporters account for on average nearly one-third of exports, 47 percent of export growth, and a third of the growth due to export diversification over a five-year period. Within countries and industries, export growth is positively correlated with the share of exports in the top five firms. Most of the top five exporters were already large five (or eight) years ago or are new firms; it is rare for these export superstars to emerge from the bottom half of the distribution of firm sizes. For countries where detailed data exist, superstars are producers, not traders, and are primarily foreign owned.