In this paper, we reconsider the theoretical basis for the Lucas critique from the point of view of robust decision theory. We first emphasize that the Lucas critique rests on a weak theoretical paradigm in that it fails to consider the motivation for the policy change by the government and hence inconsistently assumes limited rationality by the government. When placed in a proper dynamic general equilibrium framework of a dynamic game between the government and the private sector, much of the force of the critique simply vanishes. We also reconsider the critique by adopting an alternative theoretical paradigm and notion of rationality based on robust decision theory. This view of rationality might be regarded as more relevant than the nonrobust rationality employed by Lucas and, critically, it is one in which the Lucas critique can be shown simply not to apply, provided the private sector has adopted suitably robust decision rules.

The convergence hypothesis, which is developed in the context of growth economics, asserts that the income differences across countries are transitory, and developing countries will eventually attain the level of income of developed ones. On the other hand, convergence clubs hypothesis claim that the convergence can only be realized across groups of countries that share some common characteristics. In this study, we propose a new method to find convergence clubs that combines a pairwise method of testing convergence with maximum clique and maximal clique algorithms. Unlike many of those already developed in the literature, this new method aims to find convergence clubs endogenously without depending on a-priori classifications. In a Monte Carlo simulation study, the success of the method in finding convergence clubs is compared with a similar algorithm. Simulation results indicated that the proposed method perform better than the compared algorithm in most cases. In addition to the Monte Carlo, a new empirical evidence on the existence of convergence clubs is presented in the context of real data applications.

We estimate the effects of government spending shocks during prolonged episodes of low interest rates, which we consider as proxy for the effective lower bound (ELB). Using a panel VAR model for 17 advanced countries, we find that both the government consumption and investment multipliers are significantly higher, and exceed unity, when interest rates are persistently low. Distinguishing between construction- and equipment-related government investments, we find that only the former raises output by significantly more when the ELB binds. This result can be explained by existing New Keynesian models featuring time-to-build constraints on government investment.

The behavior of the real interest rate in a general equilibrium multisector model with irreversible investment is examined. It is shown that in such a model purely sectoral shocks can lead to substantial variation in the real interest rate and other aggregate time series. A source of variation in aggregate time series that is not found in one-sector models is thus examined, and the implications of this source of variation for the behavior of the interest rate are highlighted. Such a model seems to better capture the relationship among the real interest and output or investment than the standard one-sector stochastic growth model. It is also shown that, because of a desire to smooth consumption, with irreversible investment a rise in uncertainty concerning the future return to capital tends to lead to more current investment and a lower real interest rate.

This paper explores the main determinants of productivity growth. The analysis is performed using Spanish firm-level data. We define a framework where the relative magnitudes of alternative, but not exclusive, sources of technical change are simultaneously estimated. Our main finding is that the average total factor productivity (TFP) growth is fully explained by embodied technical progress (i.e., either new capital goods or human capital). Our results contradict the existence of a positive contribution of economywide neutral technological progress in determining average TFP growth. They also leave little room for large, unpriced effects external to the firm, both at the aggregate and at the industry level. We find evidence of firm-specific learning by doing, short-lived and due to adoption of new processes.

This study estimates the response of macroeconomic variables to stock market fluctuations in Japan and the United States. It emphasizes the economy's reaction to stock market bubbles and crashes. To do this, I propose a new way to identify bubbles and crashes by testing price-to-fundamental ratios using the newly developed trend-filtering approach. Regardless of the measures used, both countries' macroeconomy tends to respond positively to the positive shock of stock price. Asymmetric effects of the stock market are observed. Japan's macroeconomic variables, especially investment and industrial production, are more sensitive to market crashes, while those of the United States are more sensitive to stock bubbles. Finally, I provide evidence that market sentiment can affect the economy either directly or indirectly through the stock market.

We show that dependence on foreign energy can increase economic instability by raising the likelihood of equilibrium indeterminacy, hence making it easier for fluctuations driven by self-fulfilling expectations to occur. This is demonstrated in a standard neoclassical growth model. Calibration exercises, based on the estimated share of imported energy in production for several countries, show that the degree of reliance on foreign energy for many countries can easily make an otherwise determinate and stable economy indeterminate and unstable.

Many tests have rejected the implications of the consumption CAPM for data on U.S. asset returns. All of the tests, though, assume that the pricing errors satisfy the Central Limit Theorem. I provide empirical evidence that the marginal distributions of the pricing errors are so heavy-tailed that they do not satisfy the Central Limit Theorem. Using recent work on jackknifing, I construct a method of testing asset pricing models with heavy-tailed errors. Using this procedure, I find that the consumption CAPM is not rejected by annual U.S. data.

Christopher Sims is a well-known intellectual leader in time-series econometrics and applied macroeconomics. Among his many honors and distinctions, he has been the President of the Econometric Society and he is a member of the National Academy of Sciences. He has made fundamental contributions to both statistical theory of time series and empirical macroeconomics. Sims' work is influential precisely because it was motivated by important problems in macroeconomics. Not only did Sims study questions of statistical approximation in abstract environments, he showed how to apply the resulting apparatus to a variety of specific problems confronting applied researchers. The applications include seasonality in economic time series, aggregation over time, and approximation in formulating statistical models with economic underpinnings. Moreover, Sims' contributions to causality in time series and to the development of vector autoregressive methods were complemented by an important body of empirical research. Sims has served as an effective advocate and critic of the extensively used vector autoregressive statistical methods. Motivated by his own and related empirical research, Sims is one of the leaders in rethinking how monetary policy should be modeled and reconsidering the channels by which monetary policy influences economic aggregates. This interview with Chris Sims gives an opportunity to explore further the context of many of these contributions. Sims typically has a unique perspective on many economic problems, a perspective that is articulated in his answers to a variety of questions.

This paper examines the mechanisms through which government spending affects the dynamics of the real exchange rate. Using a two-sector dependent open economy model with intersectoral mobility costs for private capital, we show that public investment generates (i) a nonmonotonic U-shaped adjustment path for the real exchange rate with sharp intertemporal trade-offs and (ii) a crowding-in of private consumption, consistent with stylized facts. The effects of public consumption, however, are in sharp contrast to those of public investment. The effect of government spending on the real exchange rate depends critically on (i) the sectoral composition of public spending, (ii) the underlying financing policy, (iii) the sectoral intensity of private capital in production, (iv) the relative sectoral productivity of public infrastructure, (v) the elasticity of substitution in production, and (vi) intersectoral mobility costs for capital. In deriving these results, we identify conditions under which the predictions of the neoclassical open economy model can be reconciled with empirical regularities. Our results underscore the importance of decoupling the effects of government investment from those of government consumption in understanding the relationship between fiscal policy and the real exchange rate.

The relationship between recessions and productivity growth has been the focus of an important body of theoretical and empirical research in the last two decades. We contribute to this literature by presenting new evidence on the evolution of productivity in the aftermath of recessions. Our method allows us to distinguish between frontier and (in-)efficiency effects of recessions. We present international evidence for a panel of 70 countries for the period 1960–2000. Our results reveal that the average cumulative impact of recessions on productivity up to four years after their end is negative and significant. This, however, results from a mixture of mechanisms. The level of frontier production increases, but the rate of technical progress decreases, leading to a fall in frontier production. Efficiency also falls, lending support to the idea that recessions tend to reduce, rather than increase, economic restructuring. Long and deep recessions are also shown to have distinctive impacts on productivity.

This paper presents a quantitative analysis of the model developed by Galor and Moav [Galor, Oded and Omer Moav (2002) Natural selection and the origin of economic growth. Quarterly Journal of Economics 117(4), 1133–1191] in which agents vary genetically in their preference for quality and quantity of children. The simulation produces a pattern of income and population growth that resembles the period of Malthusian stagnation before the Industrial Revolution and the take-off into a modern growth era. We also investigate the stability of the modern growth era as an absorbing state of the model under the introduction of a strongly quantity-preferring genotype. We show that, given the absence of a scale effect of population in the model, the economy can regress to a Malthusian state under this change in the initial distribution of genotypes.

We analyze the importance of the frequency of decision making for macroeconomic dynamics, in the context of a simple, well-known business cycle model with balanced budget rules. We explain how the frequency of decision making (period length) and the measurement unit of time (calibration frequency) differ and examine how local stability is affected by changes in the period length. We find that as the period grows longer, indeterminacy occurs less often. This may have significant quantitative implications: for the model at hand, there is a wide range of economically relevant labor tax rates (from 30% to 38%) for which the continuous-time model gives indeterminacy, whereas the discrete-time model has determinate dynamics.

We assess the macroeconomic effects of a sovereign restructuring in a small economy belonging to a monetary union by simulating a dynamic general equilibrium model. We compare the macroeconomic outcome of restructuring with scenarios where the debt reduction is achieved via fiscal adjustment. In line with the empirical evidence, we assume that the sovereign debt is held by domestic agents and by agents in the rest of the monetary union; after the restructuring the sovereign borrowing rate increases and the increase is fully transmitted to the domestic households' borrowing rate; and the government cannot discriminate between domestic and foreign agents when restructuring. We also assume that the small economy does not exit from the monetary union after the restructuring and that the restructuring does not have systemic effects on the rest of the union. Our results suggest that the restructuring can imply persistent and large reduction of output, especially if the share of public debt held domestically is large, the private foreign debt is high, and the spread paid by the government and the households does increases.

This paper estimates Taylor rules featuring instabilities in policy parameters and switches in policy shocks’ volatility for the post-World War II (WWII) U.S. economy. We contrast a rule embedding a fixed-inflation target with another featuring trend inflation, i.e., a time-varying inflation target. The rule embedding trend inflation turns out to be (a) empirically superior according to a marginal likelihood-based comparison and (b) more able to pin down some relevant episodes of the post-WWII U.S. monetary policy history. Estimates conducted with Greenbook data confirm the empirical superiority of the rule featuring a time-varying inflation target. A comparison with recently published estimates of trend inflation is also conducted.

The fraction of the labor force under 35, or youth share, has been correlated with cyclical GDP volatility over the past several decades. The youth share and business cycle fluctuations were high during the 1970s. Then, as the population aged, output volatility declined. I develop an overlapping generations model featuring search frictions and productivity shocks, in which the age distribution affects cyclical volatility through two channels. First, employment for younger workers fluctuates more, creating a composition effect. Second, inexperienced workers produce less, so firms decide how many jobs to create based on the age distribution. Both this endogenous response by firms and the composition effect increase aggregate volatility when the youth share is high. The model can replicate a large portion of the Great Moderation in GDP volatility, suggesting an important role for demographics. The model also replicates unemployment rates, separation rates, and employment volatility by age group.

We analyze a Ramsey economy in which gross investment is constrained to be nonnegative. We prove the existence of a competitive equilibrium for the case in which utility need not be bounded from below and the Inada-type conditions need not hold. The analysis is carried out by means of a direct and technically standard approach. This direct approach allows us to obtain detailed results concerning properties of competitive equilibria, and is easily adapted for the analysis of analogous models often found in macroeconomics.

The concept of E-stability is widely used as a learnability criterion in studies of macroeconomic dynamics with adaptive learning. In this paper, it is demonstrated, via a counterexample, that E-stability generally does not imply learnability of rational expectations equilibria. The result indicates that E-stability may not be a robust device for equilibrium selection.

The initial government debt-to-gross domestic product (GDP) ratio and the government's commitment play a pivotal role in determining the welfare-optimal speed of fiscal consolidation in the management of a debt crisis. Under commitment, for low or moderate initial government debt-to-GDP ratios, the optimal consolidation is very slow. A faster pace is optimal when the economy starts from a high level of public debt implying high sovereign risk premia, unless these are suppressed via a bailout by official creditors. Under discretion, the cost of not being able to commit is reflected into a quick consolidation of government debt. Simple monetary–fiscal rules with passive fiscal policy, designed for an environment with “normal shocks,” perform reasonably well in mimicking the Ramsey-optimal response to one-off government debt shocks. When the government can issue also long-term bonds—under commitment—the optimal debt consolidation pace is slower than in the case of short-term bonds only, and entails an increase in the ratio between long- and short-term bonds.

In constitutional democracies, laws take time to be deliberated upon, to be passed, and to be implemented. Motivated by this observation, we study the properties of optimal tax reform when it has to be announced in advance of its implementation. We find that a delay between announcement and implementation has large effects on the optimal fiscal policy during the transition to the new steady state. On the other hand, we find that the welfare gains from optimal tax reform are fairly robust to the introduction of an implementation lag. Increasing the lag from zero to four years reduces the welfare gains by less than a quarter. Moreover, it turns out that this reduction of the welfare gain is mainly due to the delay itself rather than the effect of preannouncement on the character of the optimal tax reform.