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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
Are technology improvements contractionary?
We construct a measure of aggregate technology change, controlling for imperfect competition, varying utilization of capital and labor, and aggregation effects. On impact, when technology improves, input use falls sharply, and output may fall slightly. With a lag of several years, inputs return to normal and output rises strongly. These results are inconsistent with frictionless dynamic general equilibrium models, which generally predict that technology improvements are expansionary, with inputs and (especially) output rising immediately. However, the results are consistent with plausible ...
Working Paper
Uncertainty shocks in a model of effective demand
Can increased uncertainty about the future cause a contraction in output and its components? An identified uncertainty shock in the data causes significant declines in output, consumption, investment, and hours worked. Standard general-equilibrium models with flexible prices cannot reproduce this comovement. However, uncertainty shocks can easily generate comovement with countercyclical markups through sticky prices. Monetary policy plays a key role in offsetting the negative impact of uncertainty shocks during normal times. Higher uncertainty has even more negative effects if monetary ...
Working Paper
The case of the missing productivity growth: or, does information technology explain why productivity accelerated in the United States but not the United Kingdom?
Solow's paradox has disappeared in the United States but remains alive and well in the United Kingdom. In particular, the U.K. experienced an information and communications technology (ICT) investment boom in the 1990s in parallel with the U.S., but measured total factor productivity has decelerated rather than accelerated in recent years. We ask whether ICT can explain the divergent TFP performance in the two countries. Stories of ICT as a 'general purpose technology' suggest that measured TFP should rise in ICT-using sectors (reflecting either unobserved accumulation of intangible ...
Working Paper
Why is productivity procyclical? Why do we care?
Productivity rises in booms and falls in recessions. There are four main explanations for this procyclical productivity: (i) procyclical technology shocks, (ii) widespread imperfect competition and increasing returns, (iii) variable utilization of inputs over the cycle, and (iv) resource reallocations. Recent macroeconomic literature views this stylized fact of procyclical productivity as an essential feature of business cycles because each explanation has important implications for macroeconomic modeling. In this paper, we discuss empirical methods for assessing the importance of these four ...
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 ...
Journal Article
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 they 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 the long run, the one-sector model falls short empirically, reflecting the importance of rapid technological 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 ...