Knowledge that Transforms

We provide a model connecting the global saving glut to productivity growth. The key feature is that the tradable sector is the engine of growth of the economy. Capital flows from developing countries to the United States boost demand for US nontradable goods, inducing a reallocation of US economic activity from the tradable sector to the nontradable one. In turn, lower profits in the tradable sector lead firms to cut back investment in innovation. Since innovation in the United States determines the evolution of the world technological frontier, the result is a drop in global productivity growth. (JEL E21, E22, E23, E44, F32, F43, O31)

We conducted a randomized trial among 14,545 households in rural Burkina Faso to test the oft-cited hypothesis that limited access to contraception is an important driver of high fertility rates in West Africa. We do not find support for this hypothesis. Women who were given free access to modern contraception for three years did not have lower birth rates; we can reject even modest effects. We cross-randomized additional interventions to address inefficiencies that might depress demand for free contraception, specifically misperceptions about the child mortality rate and social norms. Free contraception did not significantly influence fertility even in combination with these interventions. (JEL D12, J13, J16, J18, O12)

We measure how cuts to public procurement propagate through the banking system in a financial crisis. During the European sovereign debt crisis, the Portuguese government cut procurement spending by 4.3 percent of GDP. We find that this cut saddled banks with nonperforming loans from government contractors, which led to a persistent reduction in credit supply to other firms. We estimate a bank-level elasticity of credit supply with respect to procurement demand of 2.5. In a general equilibrium model, our findings point to large effects of fiscal policy on credit supply and output in a crisis. (JEL E23, E44, E62, G01, G21, H57)

Coasts contain a disproportionate share of the world's population, reflecting historical advantages, but environmental change threatens a reversal of coastal fortune in the coming decades as natural disasters intensify and sea levels rise. This paper considers whether large infrastructure investments should continue to favor coastal areas. I estimate a dynamic spatial equilibrium framework using detailed geo-referenced data on road investments in Vietnam from 2000 to 2010 and find evidence that coastal favoritism has significant costs. The results highlight the importance of accounting for the dynamic effects of environmental change in deciding where to allocate infrastructure today. (JEL H54, O18, P25, Q54, R11, R42, R58)

This paper identifies a credit-supply contraction that arises endogenously after trade liberalization. Banks with loan portfolios concentrated in sectors exposed to competition from China face an increase in nonperforming loans after China’s entry into the World Trade Organization. As a result, they reduce the supply of credit to firms, irrespective of the firm’s sector of operation. This cut in credit translates into lower employment, investment, and output. Through this mechanism, the financial channel amplifies the shock to firms already hit by import competition from China and passes it on to firms in sectors expected to expand upon trade liberalization. (JEL D22, F14, G21, G31, G32, L25, P33)

This paper examines how central bank policies influence mortgage pricing in the United Kingdom. It shows that lenders price discriminate by offering two-part tariffs of interest rates and origination fees, and during unconventional monetary policies like the Funding for Lending Scheme, lenders reduced interest rates while increasing fees. Using a model of mortgage demand and lender competition, we find that central bank policies increased mortgage lending. Additionally, banning origination fees would reduce lending, as fees help lenders capture surplus while allowing them to price discriminate across borrowers with different sensitivities to rates and fees. (JEL E43, E52, E58, G21, G28, R31)

Ethnically diverse countries are more prone to conflict, but why do some groups engage in conflict, while others do not? I show that civil conflict in Africa is explained by ethnic groups’ cultural distance to the central government: an increase in cultural distance, proxied by linguistic distance, increases an ethnicity’s propensity to fight over government power. To identify this effect, I leverage within-ethnicity variation in linguistic distance resulting from power transitions between ethnic groups over time. I provide evidence that the effects can be attributed to differences in preferences over both the allocation and the type of public goods. (JEL D74, H41, J15, N47, O15, O17, Z13)

Software is one of the most important assets that needs to be priced in the digital economy. It has emerged as a disruptive technology, with companies primarily valued for their software offerings growing from 2 percent to 13 percent of market share between 1996 and 2023. We document persistent anomalies in growth forecasts and stock returns for software companies, indicating significant deviations from rational expectations over multiple decades. Our findings are consistent with Bayesian investors gradually learning about software’s growing importance, highlighting how markets can be very slow to discern fundamental shifts from transient shocks in noisy data. (JEL D22, G12, G32, L14, L86)

Galí (2014) showed that a monetary policy rule that raises rates when bubbles exceed some steady-state benchmark can paradoxically lead to larger deviations from steady state. Nevertheless, this comment shows that a central bank can always dampen a bubble by setting a higher-than-expected rate, although it may have to raise the rate aggressively. This is a different point from the Miao, Shen, and Wang (2019) comment on Galí (2014). They showed that when the central bank targets a different steady state than Galí considered, raising rates when bubbles exceed this alternative benchmark leads to smaller deviations from steady state. (JEL E13, E32, E44, E52, G12)

Military spending has large and persistent effects on output because it shifts the composition of public spending toward R&D. This boosts innovation and private investment in the medium term and increases productivity and GDP at longer horizons. Public R&D expenditure stimulates economic activities beyond the business cycle even when it is not associated with war spending. In contrast, the effects of public investment are shorter-lived, while public consumption has a modest impact at most horizons. We reach these conclusions using BVAR with long lags and 125 years of US data, including newly reconstructed series of government spending by main categories since 1890. (JEL E21, E22, E23, E62, H50, H56, O30)