Returns to Scale, Productivity and Competition: Empirical Evidence from U.S. Manufacturing and Construction , Establishments∗ ∗∗
Wei Gao∗ and Matthias Kehrig†
May 1, 2017
Abstract We build a model of firm entry and exit and show how returns to scale shape firm survival, the equilibrium productivity and size distributions and firm concentration. High productivity dispersion and high concentration ratios need not reflect inefficiencies when returns to scale are strongly decreasing. We apply a broad set of structural and reduced-form estimation techniques to establishment-level data from the U.S. Census of Construction and Manufacturing to assess returns to scale and productivity dispersion across establishments. Indeed, industries with lower returns to scale are characterised by higher productivity dispersion and lower concentration ra- tios as predicted in the model. Returns to scale are 0.96 on average, but range from 0.86 in Non-metallic Minerals to 1.3 in Semiconductors. Returns to scale tend to be highest in durable manufacturing, medium in non-durable manufacturing and lowest in the production of housing. An economy characterised by such differences in its sectoral production structure will exhibit long-run structural change away from construction and non-durable manufacturing, as in the data, and endogenously replicate the cyclical behavior of relative prices in the U.S.: relative durables prices are countercyclical while relative housing prices are procyclical.
Jel Codes: E2, L1, L2, L6, L7
Keywords: Returns to scale, production functions, productivity dispersion, sectoral change.
∗We are very grateful to Morris Davis and John Haltiwanger for helpful comments and discussions. Morris Davis gracefully shared several of his datasets on regional housing price indexes. Michael Blake and Susan Bucci provided help with the Census of Construction Industries. All errors are our own. The latest version of this paper can be downloaded at http://papers.ssrn.com/abstract=2731596 ∗∗Any opinions and conclusions expressed herein are those of the authors and do not necessarily represent the views of the U.S. Census Bureau. All results have been reviewed to ensure that no confidential information is disclosed. ∗University of Texas at Austin, [email protected]. †Corresponding Author, University of Texas at Austin, Department of Economics, 2225 Speedway Stop C3100, Austin, TX 78712-1690, [email protected].
1 1 Introduction
Differences across firm productivity are large and pervasive. Syverson(2004) documents that within narrowly defined U.S. industries the establishment at the top decile of the total factor productivity (TFP) distribution produces almost twice the output produced by the firm at the bottom decile of the TFP distribution that uses the same amount of inputs. That this remarkable heterogeneity in productivity is not only large but also persistent has been documented in various industries, countries and time periods (see Syverson(2011) for an overview). This heterogeneity has attracted a lot of attention recently when several studies quantified this heterogeneity result in significant efficiency losses, see for example Restuccia and Rogerson(2008); Hsieh and Klenow (2009). Consistent with this view, a large literature has argued that reallocation of resources away from the unproductive tail of the distribution to the top would increase efficiency, output and welfare (see for example Bloom et al.(2012); Akcigit et al.(2013)). But to what extent dispersion in TFP persist depends on the long-run productivity charac- teristic of an industry: returns to scale. Firms with a low total factor productivity may survive competition with their more productive peers when returns to scale are strongly decreasing; then, small size compensates for low TFP. Although there has been a lot of empirical work documenting the existence of TFP dispersion, its cyclical fluctuations and how it affects macroeconomic out- comes, there is much less using the same micro-level data to document returns to scale. This paper fills that gap and empirically studies returns to scale across a large set of U.S. construction and manufacturing industries. We utilize several methods to estimate returns to scale at the industry level and document how returns to scale vary with TFP dispersion and other characteristics of competition in the industry such as the equilibrium size distribution and firm concentration. We also study the impact of returns to scale on firm survival, productivity dispersion and firm concentration theoretically. To do that, we build a model of firm entry and exit where returns to scale differ across industries and so do equilibrium productivity dispersion and concentration ratios etc. We use the rich industry data to empirically support the predictions of main of our model: Indeed, industries with lower returns to scale are characterised by higher productivity dispersion and lower concentration ratios as predicted in the model. These results mean that one needs to be careful when assessing the efficiency and welfare consequences of measured productivity dispersion and firm concentration. When returns to scale are strongly decreasing, reallocation of resources to productive larger firms may do more harm than good. Knowing the empirics of returns to scale is important for a number of additional reasons: First, a recent strand of macro models builds “micro-founded” models, that is, frictions and economic behaviour are modelled at the level of the firm and then aggregated into macroeconomic outcomes. There is a heated debated whether or not heterogeneity across firms matters for macro aggregates or not: Khan and Thomas(2008); Thomas(2002); Bloom et al.(2012); Bloom(2009); Bachmann et al.(2013). Whether firm-level heterogeneity matters for macroeconomic aggregates crucially depends on returns to scale at the firm level because it shapes the curvature of the profit
2 function. Typically, the literature calibrates a firm-level production function. Yet, we know little of the empirical counterpart, the production function estimated using firm-level data. In this paper, we attempt to use micro-level data and estimate returns to scale for a large part of the economy. While we find that most industries are characterised by moderately decreasing returns to scale of 0.94, there is considerable heterogeneity across industries: non-metallic minerals show returns to scale on the lower end while semiconductors have significantly increasing returns to scale of 1.3. Second, returns to scale matter for the shape of the cost curve and thus supply curve. Differences in returns to scale will then translate into differences in relative prices and how they change over the business cycle. Changing relative prices have traditionally been attributed to exogenously asymmetric technology shocks. There is a large literature for example on biased technology shocks, most notably investment-specific technology shocks (see Justiniano et al.(2010, 2011); Basu et al. (2010)). This literature explains a considerable share of aggregate fluctuations with exogenous shocks to the technology of investment goods (durable manufacturing) which are identified as fluctuations in the relative price of durable goods. While this explanation is consistent with the data, we complement that view with supply-side differences in returns to scale which equally lead to the observed movement in relative prices when the economy is hit by short-run symmetric demand fluctuations. Indeed, we find that durable goods industries tend to exhibit the highest returns to scale while construction, the production of new housing, tends to exhibits the lowest returns to scale. If markups in all these industries behave similarly over the cycle, then the relative price of industries with higher returns to scale (such as durable manufacturing goods) would fall while that of industries with lower returns to scale (such as construction) would rise. Thus, short-run fluctuations in the relative price of durables could emerge from demand fluctuations that move along supply curves with different slopes. Productivity studies using micro data have traditionally focused on the manufacturing sector. We are among the first to assess returns to scale and productivity among construction establish- ments. Understanding the productivity characteristics of construction will help understand the cost structure of firms that sector of the economy, an important aspect in the pricing of these firms. Considering the supply-side factors in the housing sector of the economy has been very limited (Saiz(2010) is a notable exception) and we contribute to that literature. It seems important to understand supply-side factors because pervisou research (Glaeser et al.(2012, 2013) among others) find that demand-side factors such as low interest rates, easy access to credit cannot explain the bulk of the housing price fluctuations. Third, a long-standing literature since Marschak and Andrews(1944) has tried to estimate production functions. Assessing returns to scale has been a long and contentious debate surrounding the proper identification of production functions (see among others Burnside et al.(1995); Bils and Klenow(1998); Hall(1990); Basu and Fernald(1997); Basu(1996); Burnside(1996)). As a consequence, researchers in industrial organization have developed structural estimation techniques that overcome endogeneity and selection problems in the estimation of production functions: Olley
3 and Pakes(1996); Levinsohn and Petrin(2003); Ackerberg et al.(2015); Wooldridge(2009); Gandhi et al.(2013); Grieco et al.(forthcoming). We apply most of these estimators to a large set of establishment-level data and compare the estimation techniques in terms of their results and their computational stability. Previous research has estimated returns to scale using industry-level data (Basu and Fernald(1995, 1997); Burnside et al.(1995); Burnside(1996)) or focused on a particular industry (Olley and Pakes(1996)). To date, a comprehensive estimation of establishments-level returns to scale in the U.S. economy is missing and we fill this gap. In addition to that, we add to the empirical literature to broaden the scope beyond manufacturing which often is the main sector of analysis (Burnside(1996)).
2 Theoretical motivation
We are interested in how returns to scale and productivity matter for the the competitive environ- ment where firms struggle for survival. To assess the impact of returns to scale, we construct a heterogeneous firm model with firm entry and exit. This model is a simplified version from Kehrig (2015), but it suffices to study the relationship between returns to scale and the productivity and distribution of firms in equilibrium. Our model will feature a fixed overhead factor of production as in Melitz(2003); Ghironi and Melitz(2005) which will give rise to a survival productivity level, below which firms do not survive. The model features endogenous exit and firm-level heterogeneity in productivity. Importantly, firm survival, the measure of active firms in the economy and the size and productivity distribution in the economy will depend on the returns to scale. In the model, we adopt the assumption from Olley and Pakes(1996) that all cross-sectional profitability differences are driven by underlying technological differences rather than mark-up differences. For the purposes of studying industry characteristics of productivity and size it is enough to study this economy in partial industry equilibrium.
2.1 Firms
2.1.1 Production
A continuum of perfectly competitive firms produces a homogeneous output good which is sold to households. In period t, a measure Nt of firms is active. Each firm hires labour lit, purchases materials mit and rents capital kit in order to produce output yit using the following technology:
α γ ν yit = Atzitkitlitmit where At is an aggregate productivity level, zit is the firm’s idiosyncratic productivity and α, γ and ν are the production elasticities of all inputs. We refer to ξ α + γ + ν as the returns to scale. For ≡ the time being, we assume ξ < 1 so that the industry equilibrium does not collapse to a degernate productivity and size distribution with only one firm. Since this is a purely real model, we assume
4 that the output good is the num´eraire and normalize its price to unity. Aggregate growth and or business cycles would be driven by changes in the common productivity component, At. In line with the empirical results, we assume that each of the two productivity components follows an AR(1) stochastic process:
A A log At = (1 ρ ) log A + ρ log At 1 + ηt (1) − − z z log zit = (1 ρ ) log zi + ρ log zit 1 + εit (2) − − where ηt and εit are the aggregate and idiosyncratic components of a technology shock, respectively.
Both η and ε are drawn from a time-invariant distribution, Fη and Fε respectively. The distribution of idiosyncratic technology shocks εit is time invariant and, importantly, independent of the level of aggregate technology At. A and zi are the long-run averages of each productivity component.
Key to the production of intermediates is a fixed overhead input, denoted cf , which must be hired every period by all firms regardless of their size, productivity or other characteristics. Since overheads are required to produce at all but are not related to the production amount, it is hard to identify their impact in the data.1 Part of why that is the case is that overheads might be required in terms of any production input – capital, labour, materials, blueprints, reputation, legal licenses – or any combination of those. Examples for capital overheads could be the financing and maintenance cost of capital structures; examples of overhead labour are managerial workers, human resources, finance, organization, advertising or management etc. Regardless of their origin, these costs are most appropriately modeled as independent of the firm’s production volume decision. Though overheads are ubiquitous, we will focus on overhead labour, e.g. managers, in the model. Kehrig (2015) found empirical support to attribute some of the overheads on non-production labour. Conditional on being active and hiring overhead inputs, every firm i optimally chooses pro- duction labour, lit, capital, kit, and materials, mit, in perfectly competitive markets in order to maximize static profits
π = A z kαlγ r k w l ω c q m it t it it it − t it − t it − t f − t it where rt, wt, qt, ωt are the prices of capital, labour, materials and the overhead input in period t. Standard profit maximization leads to the firm’s factor demand:
1 1 γ ν γ ν 1 ξ α 1 γ ν α − − γ ν − r = αA z k − l m k = A z (3) t t it it it it ⇔ it t it r w q " t t t # and likewise of materials and labour. Note that firms will not optimize over overhead inputs as
1Overhead inputs are similar in nature to “intangible inputs” in that the econometrician observes more their indirect than their direct effects. Yet, researchers attribute important firm decisions to them: Atalay et al.(2014), for example, propose intangibles as a main driver of decisions of vertical integration, and Eisfeldt and Papanikolaou (2013) propose “organizational capital” – a concept similar to overhead inputs – as an important driver of a firm’s investment and financing decisions.
5 they are required as long as the firm is active at all.
2.1.2 Profitability, exit and entry
While the previous section described the optimal behavior of active firms, we also model the life- cycle pattern of firms. This seems crucial because entry and exit are at the heart of the Schumpete- rian models of business cycles. They rest on the idea that recessions are times when unproductive firms become unprofitable and are “cleansed out” of the economy. Obviously, productivity-driven exit has direct consequences for the cyclical nature of the productivity distribution. A key objective of my model is hence to feature endogenous exit along profitability. Although they are related in the present model, profitability, rather than productivity, determines whether or not a firm sur- vives. This is in line with related empirical findings by Foster et al.(2008) who document that even unproductive firms may survive as long as they are able to extract a sufficient mark-up. To understand exit along the profitability margin, it is instructive to look at maximized firm profits:
α γ ν 1 α γ ν 1 ξ π = (1 ξ) A z − ω c . (4) it − t it r w q − t f t t t Equation (4) shows that more productive firms (higher z) make larger profits and that the profit function is convex in productivity z as long as returns to scale are decreasing (0 < ξ < 1). The most productive firms then post the highest profits and the least productive firms (z close to zero) post gross profits close to zero. The overhead costs are responsible for why some unproductive firms become unprofitable at all. If there were no overhead costs, even the least productive firm would generate profits amounting to a (1 ξ)-share of their sales. When there are overheads, however, only the more productive firms − break even after paying the overheads and post positive net profits. The least productive firms, which are also the smallest producers, do not generate enough gross profits to also cover the fixed overhead costs. They become unprofitable and exit. This immediate exit can be motivated by credit constraints: firms that temporarily make negative profits will be unable to pay their production factors without credit and have to shut down operations. Alternatively, one may think that firms may become idle and “wait out” unprofitable times until the macro-economic environment becomes profitable again. Such a strategy makes sense if there are no sunk costs of re-entry. Whatsoever scenario one picks, firms that are idle or temporarily shut down operations due to lack of finance do not appear in the data and hence they would be counted as exiting firms exactly like in the present model where firms permanently exit once they become unprofitable. The convex gross profits and constant fixed overhead costs mean that there is a well-defined productivity threshold, denoted zt∗, which yield zero profits and below which firms would make
6 profits ⇡ = A z k↵l r k w l ! c it t it it it t it t it t f
negative profits: where rt,wt, !t are the prices of capital, labour and the overhead input in period t. Standard profit maximization leads to the firm’s factor demand: 1 α γ ν 1 ξ α γ ν − 1 π(zt∗) = 0 = (1 ξ) Atzt∗ ωtcf 1 1 ⇠ − r w↵ 1 q − ↵ r =t ↵A z kt l t k = A z (5) t tit it it , it t it r w 1 ξ profitsα γ ν " t t # 1 ωtcf − rt wt qt ✓ ◆ ✓ ◆ z∗ = ↵ (5)1 t ⇡ = A ↵z k l 1 r↵ k 1 ⇠ w l ! c ⇔ A 1 ξ α γ ν it t it it it t it t it t f t ↵ 1 ↵ − wt = Atzitkitlit lit = Atzit . (6) where r ,w , ! are, the prices" of capital,rt labourwt and# the overhead input in period t. 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