Research Database

We develop a model of commodity money and use it to analyze the following two questions motivated by issues in monetary history: What are the conditions under which Gresham’s Law holds? And, what are the mechanics of a debasement (lowering the metallic content of coins)? The model contains light and heavy coins, imperfect information, and prices determined via bilateral bargaining. There are equilibria with neither, both, or only one type of coin in circulation. When both circulate, coins may trade by weight or by tale. We discuss the extent to which Gresham’s Law holds in the various cases. Following a debasement, the quantity of reminting depends on the incentives offered by the sovereign. Equilibria exist with positive seigniorage and a mixture of old and new coins in circulation.

Empirical studies quantifying the economic effects of increased foreign direct investment (FDI) have not provided conclusive evidence that they are positive, as theory predicts. This paper shows that the lack of empirical evidence is consistent with theory if countries are in transition to FDI openness. Anticipated welfare gains lead to temporary declines in domestic investment and employment. Also, growth measures miss some intangible FDI, which is expensed from company profits. The reconciliation of theory and evidence is accomplished with a multicountry dynamic general equilibrium model parameterized with data from a sample of 104 countries during 1980–2005. Although no systematic benefits of FDI openness are found, the model demonstrates that the eventual gains in growth and welfare can be huge, especially for small countries.

This paper surveys the fundamental principles of subjective Bayesian inference in econometrics and the implementation of those principles using posterior simulation methods. The emphasis is on the combination of models and the development of predictive distributions. Moving beyond conditioning on a fixed number of completely specified models, the paper introduces subjective Bayesian tools for formal comparison of these models with as yet incompletely specified models. The paper then shows how posterior simulators can facilitate communication between investigators (for example, econometricians) on the one hand and remote clients (for example, decision makers) on the other, enabling clients to vary the prior distributions and functions of interest employed by investigators. A theme of the paper is the practicality of subjective Bayesian methods. To this end, the paper describes publicly available software for Bayesian inference, model development, and communication and provides illustrations using two simple econometric models.

Liabilities ceded by life insurers to shadow reinsurers (i.e., less regulated and unrated off-balance-sheet entities) grew from $11 billion in 2002 to $364 billion in 2012. Life insurers using shadow insurance, which capture half of the market share, ceded 25 cents of every dollar insured to shadow reinsurers in 2012, up from 2 cents in 2002. Our adjustment for shadow insurance reduces risk-based capital by 53 percentage points (or 3 rating notches) and increases default probabilities by a factor of 3.5. We develop a structural model of the life insurance industry and estimate the impact of current policy proposals to limit or eliminate shadow insurance. In the counterfactual without shadow insurance, the average company using shadow insurance would raise prices by 10 to 21 percent, and annual life insurance underwritten would fall by 7 to 16 percent for the industry.

We build a variation of the neoclassical growth model in which financial shocks to households or wealth shocks (in the sense of wealth destruction) generate recessions. Two standard ingredients that are necessary are (1) the existence of adjustment costs that make the expansion of the tradable goods sector difficult and (2) the existence of some frictions in the labor market that prevent enormous reductions in real wages (Nash bargaining in Mortensen-Pissarides labor markets is enough). We pose a new ingredient that greatly magnifies the recession: a reduction in consumption expenditures reduces measured productivity, while technology is unchanged due to reduced utilization of production capacity. Our model provides a novel, quantitative theory of the current recessions in southern Europe.

We develop a parsimonious model of innovating firms rich enough to confront firm-level evidence. It captures the dynamic behavior of individual heterogenous firms, describes the evolution of an industry with simultaneous entry and exit, and delivers a general equilibrium model of technological change. While unifying the theoretical analysis of firms, industries, and the aggregate economy, the model yields insights into empirical work on innovating firms. It accounts for the persistence over time of firms’ R&D investment, the concentration of R&D among incumbent firms, and the link between R&D and patenting. Furthermore, it explains why R&D as a fraction of revenues is strongly related to firm productivity yet largely unrelated to firm size or growth.

I present a behavioral epidemiological model of the evolution of the COVID epidemic in the United States and the United Kingdom over the past 12 months. The model includes the introduction of a new, more contagious variant in the UK in early fall and the US in mid December. The model is behavioral in that activity, and thus transmission, responds endogenously to the daily death rate. I show that with only seasonal variation in the transmission rate and pandemic fatigue modeled as a one-time reduction in the semi-elasticity of the transmission rate to the daily death rate late in the year, the model can reproduce the evolution of daily and cumulative COVID deaths in the both countries from Feb 15, 2020 to the present remarkably well. I find that most of the end-of-year surge in deaths in both the US and the UK was generated by pandemic fatigue and not the new variant of the virus. I then generate forecasts for the evolution of the epidemic over the next two years with continuing seasonality, pandemic fatigue, and spread of the new variant.

This paper evaluates the performances of three of the most prominent multisectoral static applied general equilibrium models used to predict the impact of the North American Free Trade Agreement. These models drastically underestimated the impact of NAFTA on North American trade. Furthermore, the models failed to capture much of the relative impacts on different sectors. Ex-post performance evaluations of applied GE models are essential if policymakers are to have confidence in the results produced by these models. Such valuations also help make applied GE analysis a scientific discipline in which there are well-defined puzzles with clear successes and failures for competing theories. Analyzing sectoral trade data indicates the need for a new theoretical mechanism that generates large increases in trade in product categories with little or no previous trade. To capture changes in macroeconomic aggregates, the models need to be able to capture changes in productivity.

We examine the quantitative impact of policy-induced changes in innovative investment by firms on growth in aggregate productivity and output in a model that nests several of the canonical models in the literature. We isolate two statistics, the impact elasticity of aggregate productivity growth with respect to an increase in aggregate innovative investment and the degree of intertemporal knowledge spillovers in research, that play a key role in shaping the model’s predicted dynamic response of aggregate productivity, output, and welfare to a policy-induced change in the innovation intensity of the economy. Given estimates of these statistics, we find that there is only modest scope for increasing aggregate productivity and output over a 20-year horizon with uniform subsidies to firms’ investments in innovation of a reasonable magnitude, but the welfare gains from such a subsidy may be substantial.

We find that the welfare gains to being at the optimum quantity of debt rather than the current U.S. level are small, and, therefore, concerns regarding the high level of debt in the U.S. economy may be misplaced. This finding is based on a model of a large number of infinitely-lived households whose saving behavior is influenced by precautionary saving motives and borrowing constraints. This model incorporates a different role for government debt than is found in standard models, and it captures different cost-benefit trade-offs. On the benefit side, government debt enhances the liquidity of households by providing an additional means of smoothing consumption and by effectively loosening borrowing constraints. On the cost side, the implied taxes have adverse wealth distribution and incentive effects. In addition, government debt crowds out capital via higher interest rates and lowers per capita consumption.