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Working Paper
What do we know and not know about potential output?
Potential output is an important concept in economics. Policymakers often use a one-sector neoclassical model to think about long-run growth, and often assume that potential output is a smooth series in the short run--approximated by a medium- or long-run estimate. But in both the short and long run, the one-sector model falls short empirically, reflecting the importance of rapid technical change in producing investment goods; and few, if any, modern macroeconomic models would imply that, at business cycle frequencies, potential output is a smooth series. Discussing these points allows us to ...
Working Paper
Aggregate productivity and aggregate technology
Aggregate productivity and aggregate technology are meaningful but distinct concepts. We show that a slightly-modified Solow productivity residual measures changes in economic welfare, even when productivity and technology differ because of distortions such as imperfect competition. We then present a general accounting framework that identifies several new non-technological gaps between productivity and technology, gaps reflecting imperfections and frictions in output and factor markets. Empirically, we find that these gaps are important, even though we abstract from variations in factor ...
Working Paper
Aggregate productivity and the productivity of aggregates
Explanations of procyclical productivity playa key role in a variety of business-cycle models. Most of these models, however, explain this procyclicaIity within a representative-firm paradigm. This procedure is misleading. We decompose aggregate productivity changes into several terms, each of which has an economic interpretation. However, many of these tenus measure composition effects such as reallocations of inputs across productive units. We apply this decomposition to U.S. data by aggregating from roughly the two-digit level to the private economy. We find that the compositional terms ...
Working Paper
Uncertainty shocks in a model of effective demand
This paper examines the role of uncertainty shocks in a one-sector, representative-agent dynamic stochastic general equilibrium model. When prices are flexible, uncertainty shocks are not capable of producing business cycle comovements among key macro variables. With countercyclical markups through sticky prices, however, uncertainty shocks can generate fluctuations that are consistent with business cycles. Monetary policy usually plays a key role in offsetting the negative impact of uncertainty shocks. If the central bank is constrained by the zero lower bound, then monetary policy can no ...
Working Paper
Productivity, welfare, and reallocation: theory and firm-level evidence
We prove that the change in welfare of a representative consumer is summarized by the current and expected future values of the standard Solow productivity residual. The equivalence holds if the representative household maximizes utility while taking prices parametrically. This result justifies total factor productivity (TFP) as the right summary measure of welfare (even in situations where it does not properly measure technology) and makes it possible to calculate the contributions of disaggregated units (industries or firms) to aggregate welfare using readily available TFP data. Based on ...
Working Paper
Constant returns and small markups in U.S. manufacturing
We estimate that returns to scale are close to constant in two-digit gross output data. Value-added data appear instead to give significant increasing returns. We show why, with imperfect competition, value-added estimates are in general meaningless. We use data on intermediate inputs to correct the value-added estimates, and find that returns to scale again appear close to constant. Given that profits are small, our results imply that markups of price over marginal cost are also small.
Working Paper
Returns to scale in U.S. production: estimates and implications
A typical (roughly) two-digit industry in the United States appears to have constant or slightly decreasing returns to scale. Three puzzles emerge, however. First, estimates tend to rise at higher levels of aggregation. Second, estimates of decreasing returns in many industries contradict evidence of only small economic profits. Third, estimates using value added differ substantially from those using gross output, and appear less robust. These puzzles are inconsistent with a representative firm paradigm, but are consistent with simple stories of aggregation over heterogeneous units. We ...
Working Paper
Endogenous volatility at the zero lower bound: implications for stabilization policy
At the zero lower bound, the central bank's inability to offset shocks endogenously generates volatility. In this setting, an increase in uncertainty about future shocks causes significant contractions in the economy and may lead to non-existence of an equilibrium. The form of the monetary policy rule is crucial for avoiding catastrophic outcomes. State-contingent optimal monetary and fiscal policies can attenuate this endogenous volatility by stabilizing the distribution of future outcomes. Fluctuations in uncertainty and the zero lower bound help our model match the unconditional and ...
Working Paper
Are technology improvements contractionary?
Yes. We construct a measure of aggregate technology change, controlling for varying utilization of capital and labor, non- constant returns and imperfect competition, and aggregation effects. On impact, when technology improves, input use and non- residential investment fall sharply. Output changes little. With a lag of several years, inputs and investment return to normal and output rises strongly. We discuss what models could be consistent with this evidence. For example, standard one-sector real-business-cycle models are not, since they generally predict that technology improvements are ...