Economists have shown that large and persistent differences in productivity levels across businesses are ubiquitous. This finding has shaped research agendas in a number of fields, including (but not limited to) macroeconomics, industrial organization, labor, and trade. This paper surveys and evaluates recent empirical work addressing the question of why businesses differ in their measured productivity levels. The causes are manifold, and differ depending on the particular setting. They include elements sourced in production practices—and therefore over which producers have some direct control, at least in theory—as well as from producers' external operating environments. After evaluating the current state of knowledge, I lay out what I see are the major questions that research in the area should address going forward.

Tremendous differences in producer productivity levels exist, even within narrowly defined industries. This paper explores the influence of product substitutability in an industry on this disparity. When consumers can easily switch between producers, inefficient (high-cost) producers cannot operate profitably. Thus high-substitutability industries should exhibit less productivity dispersion and have higher average productivity levels. I demonstrate this mechanism in a simple industry equilibrium model and test it empirically using producer-level data from 443 U.S. manufacturing industries. I find evidence that substitutability measured in several ways'is indeed negatively related to within-industry productivity dispersion and positively related to median productivity.

I thank seminar participants at the NBER Summer Institute, the Brookings Institution, and the Center for Economic Studies for their comments. Mark Roberts made several helpful suggestions regarding an earlier draft. I am also grateful to John Haltiwanger, Rachel Kranton, Mike Pries, Plutarchos Sakellaris, and John Shea for their instruction and guidance. Funding

[Financial distress can disrupt a durable goods producer's provision of complementary goods and services such as warranties, spare parts and maintenance. This reduces consumers' demand for the core product, causing indirect costs of financial distress. We test this hypothesis in the market for used cars sold at wholesale auctions. An increase in a manufacturer's credit default swaps significantly decreases the prices of its cars at auction, especially cars with longer expected service lives. Our estimates imply substantial indirect costs of financial distress for car manufacturers. These costs have occasionally even exceeded the tax savings benefits for General Motors and Ford.]

Agents are often better informed than the clients who hire them and may exploit this informational advantage. Real estate agents have an incentive to convince clients to sell their houses too cheaply and too quickly. We test these predictions by comparing home sales in which real estate agents are hired to when an agent sells his own home. Consistent with the theory, we find homes owned by real estate agents sell for 3.7% more than other houses and stay on the market 9.5 days longer, controlling for observables. Greater information asymmetry leads to larger distortions.

This paper measures the degree of monopsony power in the US higher-education labor market by using school-specific labor demand instruments to directly estimate the residual labor supply curves facing individual universities. The results indicate that schools have significant monopsony power over tenure-track faculty but face perfectly elastic residual labor supply curves for non-tenure-track faculty. There is some evidence for three sources of monopsony power often discussed in the literature—employer concentration, search frictions/job-switching costs, and differentiated jobs. The results also suggest that monopsony over tenure-track faculty may have contributed to the trend toward hiring more non-tenure-track faculty.

Three of the most fundamental changes in US corporations since the early 1970s have been (1) the increased importance of organizational capital in production, (2) the increase in managerial income inequality and pay-performance sensitivity, and (3) the secular decrease in labor market reallocation. Our paper develops a simple explanation for these changes: a shift in the composition of productivity growth away from vintage-specific to general growth. This shift has stimulated the accumulation of organizational capital in existing firms and reduced the need for reallocating workers to new firms. We characterize the optimal managerial compensation contract when firms accumulate organizational capital but risk-averse managers cannot commit to staying with the firm. A calibrated version of the model reproduces the increase in managerial compensation inequality and the increased sensitivity of pay to performance in the data over the last three decades. This increased sensitivity of compensation to performance provides large, successful firms with the glue to retain their managers and the organizational capital embedded in them.

The audit market's unique combination of features—its role in capital market transparency, mandated demand, and concentrated supply—means it receives considerable attention from policy makers. We explore the effects of two market scenarios that have been the focus of policy discussions: mandatory audit firm rotation and further supply concentration due to the exit of a “Big 4” audit firm. To do so, we first estimate publicly traded firms' demand for auditing services, allowing the services provided by each of the Big 4 to be differentiated products. We then use those estimates to calculate how each scenario would affect client firms' consumer surplus. We estimate that, for U.S. publicly trade firms, mandatory audit firm rotation would induce consumer surplus losses of approximately $2.7 billion if rotation were required after 10 years and $4.7–5.0 billion if after only four years. We find similarly that exit by one of the Big 4 would reduce client firms' surplus by $1.4–1.8 billion. These estimates reflect only the value of firms' lost options to hire the exiting audit firm; they do not include likely fee increases resulting from less competition among audit firms. The latter could result in audit fee increases between $0.75–1.3 billion per year for mandatory rotation and $0.47–0.58 billion per year for the disappearance of a Big 4 audit firm. Such losses are substantial; by comparison, total audit fees for public firms were $11 billion in 2010.