In this paper, we build on Ryan and Wales (1998) and Moschini (1999) and impose curvature conditions locally on the generalized Leontief model, introduced by Diewert (1974). In doing so, we exploit the Hessian matrix of second order derivatives of the reciprocal indirect utility function, unlike Ryan and Wales (1998) and Moschini (1999), who exploit the Slutsky matrix.

Karl Shell is without a doubt one of the central players in the development of economic theory and macroeconomics in the latter part of the twentieth century. He has made important contributions on topics ranging from growth theory, to overlapping generations, to extrinsic uncertainty, to monetary economics, to market games, and to technological innovation. His collaborations with Dave Cass are legend, and include the seminal formulation of the concept of sunspot equilibria. His “Notes on the Economics of Infinity,” and his papers with Yves Balasko are overlapping-generations classics. Shell's many coauthors read like a Who's Who in economics, and include (in no particular order) Joe Stiglitz, Franklin Fisher, Miguel Sidrauski, Ned Phelps, Duncan Foley, Walt Heller, Albert Ando, Jim Peck, Rod Garratt, Aditya Goenka, Christian Ghiglino, and Todd Keister. This is also a club to which we are also proud to belong.

Shell's research is first rate and highly innovative, but his full contribution to economic theory must also be judged by his long service as the editor of one of the profession's premier journals, the Journal of Economic Theory. As the founding editor of JET, Shell took a small upstart journal, originally envisioned as a niche outlet for papers on mathematical economics, and turned it into one of the best in the profession. JET has published papers that have had major impacts on the development of economic theory in all its various flavors.

Because of Shell's long stewardship of JET, the story of his professional life—which we hope we have captured in this interview—is also a history of the evolution of economic theory over the past quarter century. We spoke with Karl in his office at Cornell University and over lunch at the faculty club in the Statler, and the interview tapes we made were very much a three-way conversation between Karl and the two of us. In editing the transcripts of these tapes for publication, we wished to keep the focus of the conversation on Shell, and have therefore adopted the same anonymous “MD” moniker we used in our interview of Dave Cass to mask the identity of the questioner. We hope you enjoy the conversation as much as we did.

To what extent did deviations from the Taylor rule between 2002 and 2006 help to promote price stability and maximum sustainable employment? To address that question, I estimate a New Keynesian model with unemployment and perform a counterfactual experiment where monetary policy strictly follows a Taylor rule over the period 2002:Q1–2006:Q4. I find that such a policy would have generated a sizeable increase in unemployment and resulted in an undesirably low rate of inflation. Around mid-2004, when the counterfactual deviates the most from the actual series, the model indicates that the probability of an unemployment rate greater than 8% would have been as high as 80%, whereas the probability of an inflation rate above 1% would have been close to zero.

We provide aggregate macroeconomic evidence on how, in the long run, a diverse degree of complexity in production may affect not only the rate of economic growth, but also the correlation between the latter, population growth and the monopolistic (intermediate) markups. For a sample of Organisation for Economic Co-operation and Development (OECD) countries, we find that the impact of population change on economic growth is slightly positive. According to our theoretical model, this implies that the losses due to more complexity in production are lower than the corresponding specialization gains. Using a finite mixture model, we also classify the countries in the sample and verify for each cluster the impact that the population growth rate and the intermediate sector’s markups exert on the 5-year average real gross domestic product (GDP) growth rate.

In this paper, we apply two novel methodological approaches, Tucker three-way principal component analysis and locally weighted principal component analysis, to construct financial conditions index for Eurozone countries. The aim is to point out how real and financial macroeconomic variables affect the credit channel and which variables are more relevant in each occasion, highlighting structural differences within the Eurozone. The results suggest that the Eurozone is involved into a low easing pattern, which is difficult to reverse and affects considerably the financial conditions, surrounding the hypothesis that this pattern has been worsened by structural differences between the European Monetary Union (EMU) countries. Empirical evidence shows that European Central Bank (ECB) policy has managed to cool financial tensions and has made financial conditions homogeneous, but it has not been able to restore them at a precrisis level.

This paper studies a growth model with public and private education alternatives. The impact of education vouchers on economic growth and the evolution of income inequality are considered. Results indicate that introducing education vouchers can increase economic growth. Households switching from public to private education experience higher incomes. This raises the tax base, in turn raising public education expenditures and growth of the whole economy. Vouchers are found to generally increase income inequality. Welfare comparisons show that voucher schemes may in some cases gain majority support, depending on assumptions and parameters. The results add a new dimension on which vouchers can be evaluated in the continuing policy debate.

We investigate sources of economic fluctuations in Chile during 1998–2007 within the framework of a standard neoclassical growth model with time-varying frictions (wedges). We analyze the relative importance of efficiency, labor, investment, and government/trade wedges for business cycles in Chile. The purpose of this exercise is twofold: (i) focusing the policy discussion on the most important wedges in the economy and (ii) identifying which broad class of models would present fruitful avenues for further research. We find that different wedges have played different roles during our studied period, but that the efficiency, labor, and investment wedges have had the greatest impact. We also compare our results with existing studies on emerging and developed economies.

This paper builds a stylized simple sticky-price New Keynesian model where agents' beliefs are not homogeneous. We assume that agents choose optimal plans while considering forecasts of macroeconomic conditions over an infinite horizon. A fraction of them (boundedly rational agents) use heuristics to forecast macroeconomic variables over an infinite horizon. In our framework, we study optimal policies consistent with a second-order approximation of the policy objective from the consumers' utility function, assuming that the steady state is not distorted.

This paper examines the government spending multiplier when economic agents combine adaptive learning and knowledge about future fiscal policy to form their expectations. The analysis shows that the effects of a government spending shock substantially change when the rational expectations hypothesis is replaced by this learning mechanism. In contrast to the dynamics under rational expectations, a government spending shock in a small-scale new Keynesian DSGE model with learning crowds in private consumption and is associated with a positive comovement between real wages and hours worked. In the baseline calibration, the output multiplier under learning is above one and about twice as large as under rational expectations.

A recent finding of the SVAR literature is that the response of hours worked to a (positive) technology shock depends on the assumed order of integration of the hours. In this work we relax this assumption, allowing fractional integration in hours and productivity. We find that the sign and magnitude of the estimated responses depend crucially on the identification assumptions employed. Although the responses of hours recovered with short-run (SR) restrictions are positive in all data sets, long-run (LR) identification results in negative, although sometimes not significant responses. We check the validity of these assumptions with the Sims procedure, concluding that both LR and SR are appropriate to recover responses in a fractionally integrated VAR. However, the application of the LR scheme always results in an increase in sampling uncertainty. Results also show that even the negative responses found in the data could still be compatible with real business cycle models.

This paper quantifies the welfare gains from Social Security when individuals face uninsurable longevity risk. While past researchers have studied this basic question, we do so from a unique perspective. In contrast to traditional macroeconomic models that abstract from specific linkages between parents and children, in our model, children are born to specific parents whose longevity is uncertain. And because parental asset holdings evolve over the life of the parent, children face uninsurable bequest income risk in addition to their own longevity risk. We find that Social Security improves ex ante expected utility by 3.4% of lifetime consumption (for the second generation). Because our baseline analysis assumes full information and optimal hedging of longevity risk, we treat these welfare gains as a conservative estimate, and we show that the gains are significantly larger when individuals fail to hedge their longevity risk.

This study detects a structural break in international consumer price index (CPI) inflation comovement. We estimate the dynamic common factor models with unknown breakpoints of cross-country inflation rates and global price index of all commodities. We identify two global factors from the models: a commodity global factor and a noncommodity global factor. The former is a common factor between national inflation rates and commodity price index growth; the latter is a common factor among national inflation rates. The estimation of 29 countries’ quarterly CPI inflation data from 2001:Q1 to 2018:Q2 shows a one-time break in cross-country inflation dynamics in 2008:Q4. Thereafter, the importance of global factors in explaining the national inflation rates is remarkably increased. Furthermore, the increased global inflation synchronization is mainly driven by the larger role of the noncommodity global factor rather than that of the commodity global factor.

We generalize the normalized constant elasticity of substitution (CES) production function by allowing the elasticity of substitution to vary isoelastically with (i) the relative factor share, (ii) the marginal rate of substitution, (iii) the capital–labor ratio, (iv) the capital share, (v) the capital’s rate of return, or (vi) the capital–output ratio. Ensuing isoelastic elasticity of substitution (IEES) functions have intuitively and analytically desirable properties, for example, self-duality. Empirically, for the post-war US economy we robustly reject the CES specification in favor of the IEES alternative. Assuming the IEES production structure we find that the capital–labor elasticity of substitution has remained around 0.8–0.9 from 1948 to the 1980s, followed by a period of secular decline.

We study the competitive equilibrium of large random economies with linear activities using methods of statistical mechanics. We focus on economies with C commodities, N firms, each running a randomly drawn linear technology, and one consumer. We derive, in the limit N, C ∞ with n=N/C fixed, a complete description of the statistical properties of typical equilibria. We find two regimes, which in the limit of efficient technologies are separated by a phase transition, and argue that endogenous technological change drives the economy close to the critical point.

Monthly disaggregated US data from 1978 to 2016 reveal that exposure to news on inflation and monetary policy helps to explain inflation expectations. This remains true when controlling for household personal characteristics, perceptions of government policy effectiveness, expectations of future interest and unemployment rates, and sentiment. We find an asymmetric impact of news on inflation and monetary policy after 1983, with news on rising inflation and easier monetary policy having a stronger effect in comparison to news on lowering inflation and tightening monetary policy. Our results indicate the impact on inflation expectations of monetary policy news manifested through consumer sentiment during the lower bound period.

This paper introduces structural VAR analysis as a tool for investigating the anchoring of inflation expectations. We show that US consumers' inflation expectations are anchored in the long run because macro-news shocks are long-run neutral for long-term inflation expectations. The identification of structural shocks helps to explain why inflation expectations deviate from the central bank's target. Our results indicate that the recent decline in long-term inflation expectations does not result from deanchoring macro-news but can be attributed to downward adjustments in consumers' expectations about the central bank's inflation target.

By considering a simple endogenous growth model, we propose a new theoretical channel through which the presence of asset bubbles can promote economic growth. In the model economy, long-lived value-maximizing firms continuously improve the quality of their specific products through in-house research and development (R&D), while simultaneously new firms enter into the market. The key feature is endogenous market structure: The number of firms is endogenously determined, which leads to variation in firm size measured in terms of the scale of production at the level of an individual firm. The presence of asset bubbles unambiguously gives rise to larger firms. This allows in-house R&D expenditure to be spread over the greater numbers of goods that the firms produce, which can increase incentives to undertake in-house R&D.

This paper explores the consequences of tax enforcement policies for monetary policy. Agents may evade taxes by working in the informal sector, but they are detected with positive probability. Workers are rewarded with government benefits that are proportional to formal (taxed) work. When enforcement is imperfect and collecting taxes is costly, the optimal inflation rate is positive and inflation becomes a second-best tax. Deviations from the Friedman rule are optimal and depend on the tax enforcement policies. Using U.S. data, we compute the quantitative effect of different tax structures on inflation and interest rate. We show that different tax enforcement and government spending (benefits) policies induce different optimal outcomes for inflation and interest rates.

We study the main shocks driving current account (CA) fluctuations for the G6 economies, using a standard two-good intertemporal model. We build a structural vector autoregression model including the world real interest rate, net output (NO), the real exchange rate, and the CA and identify four structural shocks. Our results suggest four main conclusions: (i) there is substantial support for the two-good intertemporal model with time-varying interest rate, since both external supply and preference shocks account for an important proportion of CA fluctuations; (ii) temporary domestic shocks account for a large proportion of CA fluctuations, albeit smaller than in previous studies; (iii) our results alleviate the puzzle in the literature that a shock that explains little about NO changes can explain a large proportion of CA changes; (iv) the nature of the shock matters to shape the relationship between the CA and the real exchange rate.

This paper examines how innovation-led growth affects optimal monetary policy. We consider the Ramsey policy in a New Keynesian model where R&D leads to an expanding variety of intermediate goods and compare the results with those obtained when the expansion occurs exogenously. Positive trend inflation is found to be optimal under both assumptions, but much higher with profit-seeking innovation. Optimal monetary policy must be counter-cyclical in response to both technology and public spending shocks, yet the intensity of the reaction crucially depends on the presence of an R&D sector. However, the small amount of short-run deviations of prices from the non-zero trend inflation observed in response to shocks suggests inflation targeting as a robust policy recommendation.