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Working Paper
Four Stylized Facts about COVID-19
We document four facts about the worldwide COVID-19 pandemic that are relevant for those studying the impact of nonpharmaceutical interventions (NPIs) on COVID-19 transmission. First, across all countries and U.S. states that we study, the growth rates of daily deaths from COVID-19 fell from a wide range of initially high levels to levels close to zero within 20–30 days after each region experienced 25 cumulative deaths. Second, after this initial period, growth rates of daily deaths have hovered around zero or below everywhere in the world. Third, the cross section standard deviation of ...
Conference Paper
The transition to a new economy after the Second Industrial Revolution
During the Second Industrial Revolution, 1860?1900, many new technologies, including electricity, were invented. After this revolution, however, several decades passed before these new technologies diffused and measured productivity growth increased. We build a quantitative model of technology diffusion which we use to study this transition to a new economy. We show that the model implies both slow diffusion and a delay in growth similar to that in the data. Our model casts doubt, however, on the conjecture that this experience is a useful parallel for understanding the productivity paradox ...
Working Paper
Pricing-to-Market, Trade Costs, and International Relative Prices
Data on international relative prices from industrialized countries show large and systematic deviations from relative purchasing power parity. We embed a model of imperfect competition and variable markups in some of the recently developed quantitative models of international trade to examine whether such models can reproduce the main features of the fluctuations in international relative prices. We find that when our model is parameterized to match salient features of the data on international trade and market structure in the U.S., it reproduces deviations from relative purchasing power ...
Working Paper
The optimal degree of discretion in monetary policy
How much discretion should the monetary authority have in setting its policy? This question is analyzed in an economy with an agreed-upon social welfare function that depends on the randomly fluctuating state of the economy. The monetary authority has private information about that state. In the model, well-designed rules trade off society's desire to give the monetary authority discretion to react to its private information against society's need to guard against the time inconsistency problem arising from the temptation to stimulate the economy with unexpected inflation. Although this ...
Conference Paper
The optimal degree of monetary policy discretion
Working Paper
External and Public Debt Crises
The recent debt crises in Europe and the U.S. states feature similar sharp increases in spreads on government debt but also show important differences. In Europe, the crisis occurred at high government indebtedness levels and had spillovers to the private sector. In the United States, state government indebtedness was low, and the crisis had no spillovers to the private sector. We show theoretically and empirically that these different debt experiences result from the interplay between differences in the ability of governments to interfere in private external debt contracts and differences in ...
Discussion Paper
Policies to stimulate innovation
Journal Article
Taxing capital income: a bad idea
Under a narrow set of assumptions, Chamley (1986) established that the optimal tax rate on capital income is eventually zero. This study examines and extends that result by relaxing Chamley?s assumptions, one by one, to see if the result still holds. It does. This study unifies the work of other researchers, who have confirmed the result independently using different types of models and approaches. This study uses just one type of model (discrete time) and just one approach (primal). Chamley?s result holds when agents are heterogeneous rather than identical, the economy?s growth rate is ...
Journal Article
Are Phillips curves useful for forecasting inflation?
This study evaluates the conventional wisdom that modern Phillips curve-based models are useful tools for forecasting inflation. These models are based on the non-accelerating inflation rate of unemployment (the NAIRU). The study compares the accuracy, over the last 15 years, of three sets of inflation forecasts from NAIRU models to the naive forecast that at any date inflation will be the same over the next year as it has been over the last year. The conventional wisdom is wrong; none of the NAIRU forecasts is more accurate than the naive forecast. The likelihood of accurately predicting a ...
Journal Article
If exchange rates are random walks, then almost everything we say about monetary policy is wrong
The key question asked by standard monetary models used for policy analysis is, How do changes in short-term interest rates affect the economy? All of the standard models imply that such changes in interest rates affect the economy by altering the conditional means of the macroeconomic aggregates and have no effect on the conditional variances of these aggregates. We argue that the data on exchange rates imply nearly the opposite: the observation that exchange rates are approximately random walks implies that fluctuations in interest rates are associated with nearly one-for-one changes in ...