International Evidence on Vaccines and the Mortality to Infections Ratio in the Pre-Omicron Era, Economics of Disasters and Climate Change, 2023, with J. Aizenman, A. Cukierman, and Y. Jinjarak
Prior to the appearance of the Omicron variant, observations on countries like the UK that have accumulated a large fraction of inoculated individuals suggest that, although initially, vaccines have little effect on new infections, they strongly reduce the share of mortality out of a given pool of infections. This paper examines the extent to which this phenomenon is more general by testing the hypothesis that the ratio of lagged mortality to current infections is decreasing in the total number of vaccines per one hundred individuals in the pre-Omicron period, in a pooled time-series, cross-section sample with weekly observations for up to 208 countries. The main finding is that vaccines moderate the share of mortality from a given pool of lagged infections at sufficiently high levels of vaccination rates, which is essentially a favorable shift in the tradeoff between life preservation and economic performance. The practical lesson is that, in the presence of a sufficiently high share of inoculated individuals, governments can shade down containment measures, even as infections are still rampant, without significant adverse effects on mortality.
Gaps between official and excess Covid-19 mortality measures: The effects of institutional quality and vaccinations, Economic Modelling, 2022, with J. Aizenman, A. Cukierman, Y. Jinjarak and S. Nair-Desai
We evaluate quartile rankings of countries during the Covid-19 pandemic using both official (confirmed) and excess mortality data. By December 2021, the quartile rankings of three-fifths of the countries differ when ranked by excess vs. official mortality. Countries that are ‘doing substantially better’ in the excess mortality are characterized by higher urban population shares; higher GDP/Capita; and higher scores on institutional and policy variables. We perform two regressions in which the ratio of Cumulative Excess to Official Covid-19 mortalities (E/O ratio) is regressed on covariates. In a narrow study, controlling for GDP/Capita and vaccination rates, by December 2021 the E/O ratio was smaller in countries with higher vaccination rates. In a broad study, adding institutional and policy variables, the E/O ratio was smaller in countries with higher degree of voice and accountability. The arrival of vaccines in 2021 and voice and accountability had a discernible association on the E/O ratio.
Pandemic Shocks and Fiscal-Monetary Policies in the Eurozone: COVID-19 Dominance During January - June 2020, Oxford Economic Papers, 2021, with R. Ahmed, J. Aizenman, Y. Jinjarak and S. Nair-Desai
We compare the importance of market factors against that of coronavirus disease-19 (COVID-19) dynamics and policy responses in explaining Eurozone sovereign spreads. First, we estimate a multifactor model for changes in credit default swap (CDS) spreads over 2014 to June 2019. Then, we apply a synthetic control-type procedure to extrapolate model-implied changes in CDS. The factor model does very well over the rest of 2019 but breaks down during the pandemic, especially during March 2020. We find that the March 2020 divergence is well accounted for by COVID-specific risks and associated policies, mortality outcomes, and policy announcements, rather than traditional determinants. Daily CDS widening ceased almost immediately after the European Central Bank announced the Pandemic Emergency Purchase Programme, but the divergence between actual and model-implied changes persisted. This points to COVID-19 Dominance—widening spreads during the pandemic has led to unconventional monetary policies that primarily aim to mitigate short-run fears, temporarily pushing away concerns over fiscal risk.
Accounting for Global COVID-19 Diffusion Patterns, January-April 2020, Economics of Disasters and Climate Change, 2021, with R. Ahmed, J. Aizenman, Y. Jinjarak and S. Nair-Desai
Key factors in modeling a pandemic and guiding policy-making include mortality rates associated with infections; the ability of government policies, medical systems, and society to adapt to the changing dynamics of a pandemic; and institutional and demographic characteristics affecting citizens’ perceptions and behavioral responses to stringent policies. This paper traces the cross-country associations between COVID-19 mortality, policy interventions aimed at limiting social contact, and their interactions with institutional and demographic characteristics. We document that, with a lag, more stringent pandemic policies were associated with lower mortality growth rates. The association between stricter pandemic policies and lower future mortality growth is more pronounced in countries with a greater proportion of the elderly population and urban population, greater democratic freedoms, and larger international travel flows. Countries with greater policy stringency in place prior to the first death realized lower peak mortality rates and exhibited lower durations to the first mortality peak. In contrast, countries with higher initial mobility saw higher peak mortality rates in the first phase of the pandemic, and countries with a larger elderly population, a greater share of employees in vulnerable occupations, and a higher level of democracy took longer to reach their peak mortalities. Our results suggest that policy interventions are effective at slowing the geometric pattern of mortality growth, reducing the peak mortality, and shortening the duration to the first peak. We also shed light on the importance of institutional and demographic characteristics in guiding policy-making for future waves of the pandemic.
Demystifying Trade Patterns In A Fragmenting World, 2025, with T. Schulze
So-called “connector” countries have been argued to benefit from the US-China trade tensions, given their rising share in US imports. This paper draws an important distinction between trade reallocation—countries increase domestic production to substitute for declining Chinese exports to the US—and trade rerouting—countries serve as one-stop place for transshipment of Chinese exports to the US. Leveraging granular data on trade and FDI flows and global input-output linkages, focusing on six Asian countries, we first document that the connector role of these countries may reflect their growing domestic markets and Chinese supply chain reconfiguration, beyond trade rerouting from China to the US. We then zoom in on value-added components and deploy a synthetic control approach to disentangle trade reallocation from trade rerouting. While the evidence remains elusive for five of the six countries, Vietnam appears to have benefited from trade reallocation, with increased domestic content in its exports to the US in strategic sectors, instead of facilitating significant transshipment of Chinese exports to the US. Such domestic production expansion also helped increase domestic content in Vietnam’s exports to the rest of the world, and may be partly due to Chinese firms relocating to Vietnam through greenfield FDI. Despite potential short-term gains, trade reallocation increases connector countries’ vulnerability to geoeconomic fragmentation with losses to all countries in the long run.
Vietnam has experienced trade reallocation with increasing domestic value added in its strategic sector's exports to the U.S.
Gulf Cooperation Council Diversification: The Role of Foreign Investments and Sovereign Wealth Funds, 2025, with Y. Korniyenko
This paper investigates the role of cross-border investments, including by Sovereign Wealth Funds (SWFs), in driving economic growth and diversification of Gulf Cooperation Council (GCC) countries. Utilizing novel deal-level datasets, we analyze GCC cross-border investment portfolios across various dimensions such as time, geography, and industry. We show that recent years have witnessed an increase in GCC cross-border investments. While the geographic distribution of these investments remains diverse and balanced across different regions, both inward and outward investments are increasingly directed towards the services sector. The empirical results demonstrate a significant positive relationship between both cross-border inward and domestic investments on GCC real non-hydrocarbon GDP. Notably, the medium-term increase in real non-hydrocarbon GDP resulting from inward investments is three times larger than that from domestic investments. This amplification could be explained by increased inward investments in high-growth services sectors. Although domestic investments, including by SWFs, are contributing to the GCC economic transformation, their efficiency could be further enhanced by focusing on strategic partnerships with international investors and fostering a more transparent and competitive business environment. Recent shift in GCC investments in renewable and clean energy projects will further support diversification efforts.
Inward investment has the largest positive impacts on non-hydrocarbon real GDP growth in GCC.
Market Power in the Middle East, 2025, with Y. Korniyenko and A. Tohamy
The Middle East (ME) is often perceived as region with rentier economies and uncompetitive markets. Evidence of market power in the region however is scant. In this paper, we ask the following three questions: Is the ME uniquely uncompetitive? Has the evolution of market power in the region traced the global rise in market power? What government policies and actions influenced the market power in the region and can taxes be a way to even the playing field? To answer these questions, we utilize comprehensive firm-level data from Compustat between 2004 and 2022 and employ two methods for estimating markups (production function and cost-share approach). We document that market power among listed firms in the ME is higher than in the US, but on a downward trend. We find that the value-added tax (VAT) reforms introduced by some Gulf states from 2018 to 2022 resulted in a reduction of market power, an additional benefit beyond increasing fiscal space. While policymakers should continue to use available regulatory levers to achieve economic efficiency and a level playing field, VAT could be considered as an alternative instrument.
The value-added tax (VAT) reforms introduced by some Gulf states resulted in a reduction of market power, an additional benefit beyond increasing fiscal space.
Dissecting Medium-Term Growth Prospects for Asia, 2024, with N. Che; F. Diez, and A. Oeking
This paper explores Asia-Pacific's medium-term growth prospects using two approaches. First, growth accounting analysis and machine-learning estimation reveal how demographics, capital deepening, productivity, and human capital shaped Asia's growth. Second, an innovative algorithm forecasts growth by matching countries' current conditions with historically analogous periods using Dynamic Time Warping (DTW). Comparing pattern-based forecasts with traditional projections highlights economic convergence and demographic headwinds. Results show that without ambitious reforms, Asia's growth will likely moderate, though remaining the world's fastest growing region. The paper offers data-driven tools for policymakers to identify growth drivers and generate robust forecasts.
Without ambitious reforms, Asia's growth will likely moderate, though remaining the world's fastest growing region.
Political Fragility: Coups d’État and Their Drivers [Datasets and Results], 2024, with A. Cebotari, E. Chueca-Montuenga, Y. Diallo, Y. Ma, R. Turk, and H. Zavarce
The paper explores the drivers of political fragility by focusing on coups d’état as symptomatic of such fragility. It uses event studies to identify factors that exhibit significantly different dynamics in the runup to coups, and machine learning to identify these stressors and more structural determinants of fragility—as well as their nonlinear interactions—that create an environment propitious to coups. The paper finds that the destabilization of a country’s economic, political or security environment—such as low growth, high inflation, weak external positions, political instability and conflict—set the stage for a higher likelihood of coups, with overlapping stressors amplifying each other. These stressors are more likely to lead to breakdowns in political systems when demographic pressures and underlying structural weaknesses (especially poverty, exclusion, and weak governance) are present or when policies are weaker, through complex interactions. Conversely, strengthened fundamentals and macropolicies have higher returns in structurally fragile environments in terms of staving off political breakdowns, suggesting that continued engagement by multilateral institutions and donors in fragile situations is likely to yield particularly high dividends. The model performs well in predicting coups out of sample, having predicted a high probability of most 2020-23 coups, including in the Sahel region.
The recent increase in sub-Saharan African countries' coup probability is mainly driven by sociopolitical instability.
We empirically examine U.S. monetary policy spillovers to the Middle East and Central Asia (ME & CA) region by decomposing U.S. interest rates changes into two orthogonal shocks: the pure monetary policy shock and the information news shock. Using a sample of 16 ME & CA countries, we find that when interest rates increase, the two shocks have opposite spillovers on the region. Tightening driven by contractionary monetary policy shocks hinders growth, while tightening driven by positive information news shocks boosts growth despite higher interest rates. Countries with weaker fundamentals face more negative spillovers from contractionary monetary policy shocks but may sometimes benefit more from positive information news shocks. Moreover, high oil prices mitigate both spillovers for oil exporters while global risk appetite amplifies both spillovers. Finally, we estimate a large degree of heterogeneity in the impact of the 2022 U.S. tightening cycle on ME & CA countries, with oil exporters with stronger fundamentals withstanding well the shock and oil importers with weaker fundamentals being hit the most.
Contractionary monetary policy shocks decrease growth while positive information news shocks increase growth.
International Reserves, Crisis Risk, and Risk Tolerance, 2024, with Y. Feng and X. Tong, submitted
This paper investigates the link between crisis risk estimation and crisis prevention policy in the context of sudden stops with growth impacts. We propose a two-stage framework that embeds an early-warning problem into a policy-making problem, and conduct a welfare analysis of crisis risk estimation based on subsequent policy responses. Building upon this two-stage framework, we show that there is welfare cost asymmetry between two types of errors: the welfare-maximizing weight on the missed crises is greater than that on the false alarms. This paper introduces a constrained optimization problem under the Neyman-Pearson paradigm to solve this error-asymmetry problem, and conducts backtesting with multiple algorithms under this paradigm with asymmetry-warranted evaluation metric. Bringing this welfare-based two-stage framework to emerging market countries' data, we uncover the time-varying risk tolerance of policymakers.
Revealed time-varying risk tolerance which increases in the runup to sudden stops and decreases after sudden stops.
External Crisis Prediction Using Machine Learning: Evidence from Three Decades of Crises Around the World, 2019, with S. Basu and R. Perrelli [new version coming soon]
As external crises can be economically disruptive events for advanced economies, emerging markets, and low-income economies alike, predicting such crises is an important task, yet a somewhat inglorious one. In this paper, we generate crisis lists for two types of external crises — sudden stops with growth impact, and exchange market pressure events — for more than 150 countries over 28 years. We then evaluate the performance of signal extraction approach and machine learning techniques for the prediction of such crises. Bearing in mind the potentially sharp divergence between in-sample and out-of-sample performance, we design a rigorous testing procedure attuned to the temporal dependence of macro data and the manner in which the models would be used in practice. We find that for sudden stops with growth impact, the performance of signal extraction approach and machine learning techniques is comparable, and signal extraction approach sometimes performs better. For exchange market pressure events, which are more heterogeneous than sudden stops, we find that tree-based machine learning techniques do appear to perform better than signal extraction approach and regularized linear regression models. We use the output of the models to shed light on variable importance rankings and some of the critical non-monotonicities and interactions that machine learning uncovers from the historical data.
An example of interaction effect between export growth and change in FX reserves that machine learning uncovers.
Performance Uncertainty and Ranking Significance of Early-Warning Models, with S. Basu and R. Perrelli