It is customary for the Interviewer to begin with an introduction describing the circumstances of the interview and providing an overview of the nature and importance of the work of the interviewee. However, in this case, as Editor of this journal, I feel it would be presumptuous of me to provide my own overview and evaluation of the work of this great man, Paul Samuelson. The scope of his contributions has been so vast (averaging almost one technical paper per month for over 50 years) that it could be particularly difficult to identify those areas of modern economic theory to which he has not made seminal contributions.Perhaps those rare exceptions might include game theoretic and topological models and maybe the recent literatures on complex unstable nonlinear dynamics, sunspots, and incomplete markets. But I would not be surprised, if he were to correct those speculations as misperceptions, if I were to ask. In addition to his over 550 published papers, his books are legendary. He once said: “Let those who will—write the nation's laws–if I can write its textbooks.”

Instead of attempting to provide my own overview, I am limiting this introduction to the following direct (slightly edited) quotation of a few paragraphs from the Web site, The History of Economic Thought, which is maintained online by the New School University in New YorkThe current URL of that Web site is http://cepa.newschool.edu/het/home.htm.: Perhaps more than anyone else, Paul A. Samuelson has personified mainstream economics in the second half of the twentieth century. The writer of the most successful principles textbook ever (1948), Paul Samuelson has been not unjustly considered the incarnation of the economics ‘establishment’—and as a result, has been both lauded and vilified for virtually everything right and wrong about it.Samuelson's most famous piece of work, Foundations of Economic Analysis (1947), is one of the grandest tomes that helped revive Neoclassical economics and launched the era of the mathematization of economics. Samuelson was one of the progenitors of the Paretian revival in microeconomics and the Neo-Keynesian Synthesis in macroeconomics during the post-war period.The wunderkind of the Harvard generation of 1930s, where he studied under Schumpeter and Leontief, Samuelson had a prodigious grasp of economic theory, which has since become legendary. An unconfirmed anecdote has it that at the end of Samuelson's dissertation defense, Schumpeter turned to Leontief and asked, ‘Well, Wassily, have we passed?’ Paul Samuelson moved on to M.I.T. where he built one of the century's most powerful economics departments around himself. He was soon joined by R.M. Solow, who was to become Samuelson's sometime co-writer and partner-in-crime.Samuelson's specific contributions to economics have been far too many to be listed here—being among the most prolific writers in economics. Samuelson's signature method of economic theory, illustrated in his Foundations (1947), seems to follow two rules which can also be said to characterize much of Neoclassical economics since then: With every economic problem, (1) reduce the number of variables and keep only a minimum set of simple economic relations; and (2) if possible, rewrite it as a constrained optimization problem.In microeconomics, he is responsible for the theory of revealed preference (1938, 1947). This and his related efforts on the question of utility measurement and integrability (1937, 1950) opened the way for future developments by Debreu, Georgescu-Roegen, and Uzawa. He also introduced the use of comparative statics and dynamics through his ‘correspondence principle’ (1947), which was applied fruitfully in his contributions to the dynamic stability of general equilibrium (1941, 1944). He also developed what are now called ‘Bergson-Samuelson social welfare functions’ (1947, 1950, 1956); and, no less famously, Samuelson is responsible for the harnessing of ‘public goods’ into Neoclassical theory (1954, 1955, 1958).Samuelson was also instrumental in establishing the modern theory of production. His Foundations (1947) are responsible for the envelope theorem and the full characterization of the cost function. He made important contributions to the theory of technical progress (1972). His work on the theory of capital is well known, if contentious. He demonstrated one of the first remarkable ‘Non-Substitution’ theorems (1951) and, in his famous paper with Solow (1953), initiated the analysis of dynamic Leontief systems. This work was reiterated in his famous 1958 volume on linear programming with Robert Dorfman and Robert Solow, wherein we also find a clear introduction to the ‘turnpike’ conjecture of linear von Neumann systems. Samuelson was also Joan Robinson's main adversary in the Cambridge Capital Controversy—introducing the ‘surrogate’ production function (1962), and then subsequently (and graciously) relenting (1966).In international trade theory, he is responsible for the Stolper–Samuelson Theorem and, independently of Lerner, the Factor Price Equalization theorem (1948, 1949, 1953), as well as (finally) resolving the age-old ‘transfer problem’ relating terms of trade and capital flows, as well as the Marxian transformation problem (1971), and other issues in Classical economics (1957, 1978).In macroeconomics, Samuelson's multiplier-accelerator macrodynamic model (1939) is justly famous, as is the Solow–Samuelson presentation of the Phillips Curve (1960) to the world. He is also famous for popularizing, along with Allais, the ‘overlapping generations’ model which has since found many applications in macroeconomics and monetary theory. In many ways, his work on speculative prices (1965) effectively anticipates the efficient markets hypothesis in finance theory. His work on diversification (1967) and the ‘lifetime portfolio’ (1969) is also well known.Paul Samuelson's many contributions to Neoclassical economic theory were recognized with a Nobel Memorial prize in 1970.

This paper is dedicated to the memory of the great statistician Melvin J. Hinich, with whom we were in contact about this research prior to his untimely death from a tragic fall. We develop a neoclassical growth model with habit formation to exhibit an equilibrium nonlinear relationship between aggregate consumption growth and income growth. We first provide empirical evidence consistent with this relationship both for the United States and France, and we reject the hypothesis of a random walk for consumption. We then estimate this nonlinear relationship. We find for both countries robust evidence of persistence, nonlinearity, and cyclicity in the relationship between consumption and income.

The welfare cost of anticipated inflation is quantified in a matching model of money calibrated to 23 different OECD countries for several sample periods. In most economies, in the common period 1978–1998, a representative agent would give up only a fraction of 1% of consumption to avoid 10% inflation. The welfare cost of inflation varies across countries, from a fraction of 0.1% in Japan, to more than 2% in Australia, reaching 6% with bargaining. The model fits money demand data of several countries poorly, however. The fit generally improves with longer sample periods. The results are fairly robust to variations in choice of calibrated parameters and calibration targets.

This paper proposes a New Keynesian dynamic stochastic general equilibrium model of the Chinese economy incorporating the demand of oil to study the effects of oil price shocks on the business cycle. The model answers several questions, including how monetary policy should respond to the disturbances from such shocks, and whether monetary authorities should use core inflation or headline inflation including oil price inflation as the monetary policy rule. The contributions could be summarized as follows: First, the model reveals that the oil transmission mechanism is determined by the nominal inertia, income effect, and the portfolio allocation effect. Second, both noncore inflation monetary policy and core inflation monetary policy that are simultaneously pegged to oil prices fluctuations are inferior to the monetary policy purely pegged to core inflation. Our findings suggest that the monetary policy should focus on core inflation instead of headline inflation.

One part of the literature on endogenous growth concerns models where public infrastructure affects the private production process. An unsolved puzzle in this literature concerns observed public investment-to-output ratios for developed economies, which tend to fall short of theoretical model-based optimal ratios. We reexamine the optimal choice of public investment in a more general framework. This setting allows for long-lasting capital stocks, a lower depreciation rate for public capital than for private capital, an elasticity of intertemporal substitution that differs from unity, and the need to finance a nontrivial share of public services in output. Given other fundamentals in the economy, we show that the optimal public investment-to-output ratio is smaller for low-growth economies, for economies populated by consumers with low preferences for substituting consumption intertemporally, and when public capital is durable. For a calibrated economy, we show that a combination of these factors solves the public investment puzzle.

In this paper we investigate the relationship between crude oil and gasoline prices and also examine the effect of oil price uncertainty on gasoline prices. The empirical model is based on a structural vector autoregression that is modified to accommodate multivariate GARCH-in-Mean errors. We use monthly data for the United States over the period from January 1976 to September 2014. We find that there is an asymmetric relationship between crude oil and gasoline prices, and that oil price uncertainty has a positive effect on gasoline price changes. Our results are robust to alternative model specifications and alternative measures of the price of oil.

We use the longest span data that have ever been studied before (from 1870 to 2014) to investigate the relationship between the price of oil and the level of economic activity in the United States. In the context of a bivariate (identified) structural generalized autoregressive conditional heteroscedasticity (GARCH)-in-Mean VAR in real output growth and the change in the real price of oil, we find that uncertainty about oil prices has had a negative and significant effect on real output. We also find that the responses of real output growth to positive and negative shocks are not very informative of whether they are symmetric or asymmetric, and that accounting for oil price uncertainty tends to amplify the negative dynamic response of real output growth to unfavorable (positive) oil price shocks.

Seasonality has been a major research area in economics for several decades. The paper assesses the recent development in the literature on the treatment of seasonality in economics, and divides it into three interrelated groups. The first group, pure noise models, consists of methods based on the view that seasonality is noise contaminating the data or, more correctly, contaminating the information of interest for the economists. The second group, time-series models, treats seasonality as a more integrated part of the modeling strategy, with the choice of model being data driven. The third group, economic models of seasonality, introduces economic theory, that is, optimizing behavior, into the modeling of seasonality.

We examine how future real GDP growth relates to changes in the forecasted long-term average of discounted real oil prices and to changes in unanticipated fluctuations of real oil prices around the forecasts. Forecasts are conducted using a state-space oil market model, in which global real economic activity and real oil prices share a common stochastic trend. Changes in unanticipated fluctuations and changes in the forecasted long-term average of discounted real oil prices sum to real oil price changes. We find that these two components have distinctly different relationships with future real GDP growth. Positive and negative changes in the unanticipated fluctuations of real oil prices correlate with asymmetric responses of future real GDP growth. In comparison, changes in the forecasted long-term average are smaller in magnitude but are more influential on real GDP. Persistent upward revisions of forecasts in the 2000s had a substantial negative impact on real GDP growth, according to our estimates.

In the existing literature, panic-based bank runs are triggered by a commonly acknowledged and observed sunspot signal. There are only two equilibrium realizations resulting from the commonly observed sunspot signal: Everyone runs or no one runs. I consider a more general and more realistic situation in which consumers observe noisy private sunspot signals. If the noise in the signals is sufficiently small, there exists a proper correlated equilibrium for some demand deposit contracts. A full bank run, a partial bank run (in which some consumers panic whereas others do not), or no bank run occurs, depending on the realization of the sunspot signals. If the probabilities of runs are small, the optimal demand deposit contract tolerates full and partial bank runs.

We study the dynamics of risk premia in a model with external habit formation and highlight the significance of “recession predictability”. Although under the specification of Campbell and Cochrane, [Journal of Political Economy 107, 205–251 (1999)] the equity risk premium is countercyclical because increases in risk aversion are reinforced by rising recession risks, this need not be the case more generally. We show analytically that in endowment economies procyclical recession expectations can outweigh countercyclical changes in risk aversion, generating counterfactual risk-premium behavior. However, allowing shocks or habits to be sufficiently persistent, or explicitly accounting for the impact of habits on consumption, suffices to generate countercyclical recession risks and risk premia.

Benhabib et al. [(2001) Journal of Economic Theory 96, 40–69] argue that there exists a deflation steady state when the zero lower bound on the nominal interest rate is considered in a Taylor-type monetary policy rule. This paper estimates a medium-scale DSGE model with a deflation steady state for the Japanese economy during the period from 1999 to 2013, when the Bank of Japan conducted a zero interest rate policy and the inflation rate was almost always negative. Although the model exhibits equilibrium indeterminacy around the deflation steady state, a set of specific equilibria is selected by Bayesian methods. According to the estimated model, positive shocks to households’ preferences and wage markup, and a negative shock to monetary policy do not necessarily have an inflationary effect, in contrast to a standard model with a targeted-inflation steady state. An economy in the deflation equilibrium could experience unexpected volatility because of sunspot fluctuations, but it turns out that sunspot shocks have a limited effect on Japan’s output fluctuations and rather contribute to stabilizing the economy after the global financial crisis.

Nonlinear co-integration is studied for score-driven models, using a new multivariate dynamic conditional score/generalized autoregressive score model. The model is named t-QVARMA (quasi-vector autoregressive moving average model), which is a location model for the multivariate t-distribution. In t-QVARMA, I(0) and co-integrated I(1) components of the dependent variables are included. For t-QVARMA, the conditions of the maximum likelihood estimator and impulse response functions (IRFs) are presented. A limiting special case of t-QVARMA, named Gaussian-QVARMA, is a Gaussian-VARMA specification with I(0) and I(1) components. As an empirical application, the US real gross domestic product growth, US inflation rate, and effective federal funds rate are studied for the period of 1954 Q3 to 2020 Q2. Statistical performance and predictive accuracy of t-QVARMA are superior to those of Gaussian-VAR. Estimates of the short-run IRF, long-run IRF, and total IRF impacts for the US data are reported.

This paper analyzes government spending multipliers in a two-country model of a monetary union with price stickiness and home bias in consumption where monetary policy is constrained by the zero lower bound (ZLB) on the nominal interest rate. Government spending multipliers under this constraint are computed and compared with fiscal multipliers in normal times, that is, where the central bank sets the nominal interest rate via a Taylor rule. The trade elasticity and the parameter measuring home bias in consumption play an important role in determining the size of the multiplier. The multipliers are not necessarily large under the ZLB constraint. However, compared with the fiscal multipliers when the central bank sets the nominal interest rate according to a Taylor rule, the multipliers under the ZLB are bigger. Moreover, the persistence parameter of the binding ZLB plays a crucial role.

Peter Diamond is one of the major contributors to economics during the last half century. His many contributions include research on growth, Social Security, public finance more generally, the economics of uncertainty, search theory, in particular, and economic dynamics, in general. This work has shaped the way we think about many economic problems, and the way in which we formalize them. Among his long list of honors and awards, he is a fellow of the Econometric Society, a Guggenheim Fellow, a Fellow of the American Academy of Arts and Sciences, a Member of the National Academy of Sciences, and a Nemmers Prize winner. The National Science Foundation has supported his work for the last 40 years. A recent check indicated 9 books and 132 published articles, and there are few signs of any slowdown.

We examine the nexus between land transfers and human capital formation. A sequence of land redistributions enables the beneficiaries to educate their children and thus to escape from poverty. A successful land reform allows the transition of a society from an agriculture-based state of poverty to a human capital–based developed economy. We find that a temporary state of inequality among the poor is unavoidable. Finally, we discuss the political economy of land reform, whether access to land markets should be allowed for beneficiaries of land reforms, and property rights issues.

Three important current areas of research in the field of international comparisons are the construction of price indexes at the basic heading level, price indexes at higher levels of aggregation, and the linking of comparisons across regions. We consider recent innovations in each of these areas. These innovations have largely arisen out of International Comparisons Program (ICP) 2005, and hence we discuss them in this context. We give particular emphasis to the construction of price indexes at the basic heading level, because we believe it is here that the biggest problems lie. For example, the apparently anomalous results obtained for China and India in ICP 2005 can be traced back to problems at the basic heading level. We also highlight some inconsistencies in current ICP methodology and some promising areas for future research that warrant closer scrutiny in the next round of ICP.

I demonstrate that the precise timing of financial markets and goods markets in a simple cash good/credit good model does not matter for the main results in the Ramsey literature on optimal fiscal and monetary policy. In Ramsey models based on Lucas and Stokey [Journal of Monetary Economics 12, 55–93 (1983)] and Chari, Christiano, and Kehoe [Journal of Money, Credit, and Banking 23, 519–539 (1991)], nominal money holdings are freely adjustable in response to shocks in the period in which they will be used to purchase consumption. In contrast, under Svensson [Journal of Political Economy 93, 919–944 (1985)] timing, nominal balances cannot be adjusted in the period they will be used. The broad finding is that benchmark Ramsey results are not very sensitive to this slight, ultimately ad hoc, modification. In particular, optimal inflation continues to display very high variability just as in the original models, although this can differ depending on exactly which exogenous processes are driving the economy. That the basic results in the Ramsey literature are not sensitive to the choice of cash/credit timing is reassuring as Ramsey analysis is applied to an ever-expanding set of model environments.

This paper provides estimates of the welfare cost of volatility attributable to monetary and fiscal policy shocks. It uses a continuous-time stochastic dynamic general equilibrium model based on a recursive utility function that disentangles risk aversion from intertemporal substitution. We find that monetary and fiscal policy shocks may lead to opposite welfare effects: negative for monetary growth shocks, but positive for government expenditure shocks. Furthermore, we find that welfare costs are sensitive to the parameter values chosen for risk aversion and intertemporal substitution, and we conclude that welfare costs are potentially much larger than that found by Lucas, forcing some modification of the policy conclusions associated with Lucas's pioneering work.

Because they ignore the household-level and macroeconomic adjustments associated with longevity improvements, the actuarial projections of the Social Security Administration overestimate the Social Security crisis. Using a general-equilibrium model with heterogeneous households and incomplete markets, I show that with these adjustments accounted for, a significantly smaller decline in benefits is needed to balance the Social Security budget. Households respond by delaying retirement and Social Security benefit collection, by working more hours, and by also saving more. In general equilibrium, these effects lead to a natural expansion of Social Security's tax base and generate significant delayed retirement credits, which the actuarial estimates completely overlook.