Research Topics

This paper offers a retrospective view of the key pillar of Solow’s neoclassical growth model, namely the aggregate production function. We review how this tool came to life and how it has survived until today, despite three criticisms that undermined its raison d’être. They are the Cambridge Capital Theory Controversies, the Aggregation Problem, and the Accounting Identity. These criticisms were forgotten by the profession, not because they were wrong but because of the key role played by Robert Solow in the field. Today, these criticisms are not even mentioned when students are introduced to (neoclassical) growth theory, which is presented in most economics departments and macroeconomics textbooks as the only theory worth studying.

The year 2023 commemorates the 30th anniversary of the publication of the influential, yet controversial, study The East Asian Miracle report by the World Bank (1993). An important part of the report’s analysis was concerned with the sources of growth in East Asia. This was based on the neoclassical decomposition of growth into productivity and factor accumulation. At about the same time, the publication of Alwyn Young’s (1992, 1995) and J. I. Kim and Lawrence Lau’s (1994) studies, and Paul Krugman’s (1994) popularization of the “zero total factor productivity growth” thesis, led to a very important debate within the profession, on the sources of growth in East Asia. The emerging literature on China’s growth during the 1990s also used the neoclassical growth model to decompose overall growth into total factor productivity growth and factor accumulation. This survey reviews what the profession has learned during the last 30 years about East Asia’s growth, using growth-accounting exercises and estimations of production functions. It demystifies this literature by pointing out the significant methodological problems inherent in the neoclassical growth-accounting approach. We conclude that the analysis of growth within the framework of the neoclassical model should be seriously questioned. Instead, we propose that researchers look at other approaches, for example, the balance-of-payments–constrained growth rate approach of Thirlwall (1979) or the product space of Hidalgo et al. (2007), together with the notion of complexity of Hidalgo and Hausmann (2009).

This paper argues that the 40-year-old Feldstein-Horioka “puzzle” (i.e., that in a regression of the domestic investment rate on the domestic saving rate, the estimated coefficient is significantly larger than what would be expected in a world characterized by high capital mobility) should have never been labeled as such. First, we show that the investment and saving series typically used in empirical exercises to test the Feldstein-Horioka thesis are not appropriate for testing capital mobility. Second, and complementary to the first point, we show that the Feldstein-Horioka regression is not a model in the econometric sense, i.e., an equation with a proper error term (a random variable). The reason is that by adding the capital account to their regression, one gets the accounting identity that relates the capital account, domestic investment, and domestic saving. This implies that the estimate of the coefficient of the saving rate in the Feldstein-Horioka regression can be thought of as a biased estimate of the same coefficient in the accounting identity, where it has a value of one. Since the omitted variable is known, we call it “pseudo bias.” Given that this (pseudo) bias is known to be negative and less than one in absolute terms, it should come as no surprise that the Feldstein-Horioka regression yields a coefficient between zero and one.

Biased Coefficients and Endogenous Regressors, or a Case of Collective Amnesia?

The possible endogeneity of labor and capital in production functions, and the consequent bias of the estimated elasticities, has been discussed and addressed in the literature in different ways since the 1940s. This paper revisits an argument first outlined in the 1950s, which questioned production function estimations. This argument is that output, capital, and employment are linked through a distribution accounting identity, a key point that the recent literature has overlooked. This identity can be rewritten as a form that resembles a production function (Cobb-Douglas, CES, translog). We show that this happens because the data used in empirical exercises are value (monetary) data, not physical quantities. The argument has clear predictions about the size of the factor elasticities and about what is commonly interpreted as the bias of the estimated elasticities. To test these predictions, we estimate a typical Cobb-Douglas function using five estimators and show that: (i) the identity is responsible for the fact that the elasticities must be the factor shares; (ii) the bias of the estimated elasticities (i.e., departure from the factor shares) is, in reality, caused by the omission of a term in the identity. However, unlike in the standard omitted-variable bias problem, here the omitted term is known; and (iii) the estimation method is a second-order issue. Estimation methods that theoretically deal with endogeneity, including the most recent ones, cannot solve this problem. We conclude that the use of monetary values rather than physical data poses an insoluble problem for the estimation of production functions. This is, consequently, far more serious than any supposed endogeneity problems.

A Caveat Emptor for Regional Scientists

Over the last 20 years or so, mainstream economists have become more interested in spatial economics and have introduced largely neoclassical economic concepts and tools to explain phenomena that were previously the preserve of economic geographers. One of these concepts is the aggregate production function, which is also central to much of regional growth theory. However, as Franklin Fisher, inter alios, has shown, the conditions necessary to aggregate microproduction functions into an aggregate production function are so stringent that in all probability the aggregate production function does not exist. This paper shows that the good statistical fits commonly found empirically are solely due to the use of value data and an underlying accounting identity. The result is that the estimates obtained cannot be regarded as providing evidence of the underlying technological structure of the spatial economy, including the aggregate elasticity of substitution, the degree of returns to scale, and the rate of technical progress.

Further Reflections on Temple’s Criticisms and Misunderstandings

In a reply to Felipe and McCombie (2010a), Temple (2010) has largely ignored the main arguments that underlie the accounting identity critique of the estimation of production functions using value data. This criticism suggests that estimates of the parameters of aggregate production functions cannot be regarded as reflecting the underlying technology of the industry. While Temple concedes some points, he erroneously believes that the critique holds only under some ad hoc assumptions. As a consequence, he argues that the critique works only “part-time.” This rejoinder discusses Temple’s arguments and demonstrates that the critique works full-time.