On the Scientific Status of Economic Policy: A Tale of Alternative Paradigms

In the last years, a number of contributions has argued that monetary -- and, more generally, economic -- policy is finally becoming more of a science. According to these authors, policy rules implemented by central banks are nowadays well supported by a theoretical framework (the New Neoclassical Synthesis) upon which a general consensus has emerged in the economic profession. In other words, scientific discussion on economic policy seems to be ultimately confined to either fine-tuning this "consensus" model, or assessing the extent to which "elements of art" still exist in the conduct of monetary policy. In this paper, we present a substantially opposite view, rooted in a critical discussion of the theoretical, empirical and political-economy pitfalls of the neoclassical approach to policy analysis. Our discussion indicates that we are still far from building a science of economic policy. We suggest that a more fruitful research avenue to pursue is to explore alternative theoretical paradigms, which can escape the strong theoretical requirements of neoclassical models (e.g., equilibrium, rationality, etc.). We briefly introduce one of the most successful alternative research projects -- known in the literature as agent-based computational economics (ACE) -- and we present the way it has been applied to policy analysis issues. We conclude by discussing the methodological status of ACE, as well as the (many) problems it raises.Economic Policy, Monetary Policy, New Neoclassical Synthesis, New Keynesian Models, DSGE Models, Agent-Based Computational Economics, Agent-Based Models, Post-Walrasian Macroeconomics, Evolutionary Economics.

How Do Output Growth Rate Distributions Look Like? Some Time-Series Evidence on OECD Countries

This paper investigates the statistical properties of within-country GDP and industrial production (IP) growth rate distributions. Many empirical contributions have recently pointed out that cross-section growth rates of firms, industries and countries all follow Laplace distributions. In this work, we test whether also within-country, time-series GDP and IP growth rates can be approximated by tent-shaped distributions. We fit output growth rates with the exponential-power (Subbotin) family of densities, which includes as particular cases both the Gaussian and the Laplace distributions. We find that, for a large number of OECD countries including the U.S., both GDP and IP growth rates are Laplace distributed. Moreover, we show that fat-tailed distributions robustly emerge even after controlling for outliers, autocorrelation and heteroscedasticity

Are Output Growth-Rate Distributions Fat-Tailed? Some Evidence from OECD Countries

This work explores some distributional properties of aggregate output growth-rate time series. We show that, in the majority of OECD countries, output growth-rate distributions are well-approximated by symmetric exponential-power densities with tails much fatter than those of a Gaussian. Fat tails robustly emerge in output growth rates independently of: (i) the way we measure aggregate output; (ii) the family of densities employed in the estimation; (iii) the length of time lags used to compute growth rates. We also show that fat tails still characterize output growth-rate distributions even after one washes away outliers, autocorrelation and heteroscedasticity.Output Growth-Rate Distributions, Normality, Fat Tails, Time Series, Exponential-Power Distributions, Laplace Distributions, Output Dynamics.

Modelling smooth and uneven cross-sectoral growth patterns: an identification problem

This paper shows that the available stylized facts on productivity dynamics, such as persistent cross-sectoral heterogeneity, do not allow to solve an identification problem regarding the impact of common drivers - such as General Purpose Technologies (GPTs) - on economic growth. The evidence of persistently heterogeneous productivity performances is consistent both with a GPT-driven model, and with a model characterized by purely independent and idiosyncratic sectoral dynamics. These results are obtained within a simple theoretical framework, and illustrated with reference to measures of concentration of the sectoral contributions to aggregate total factor productivity growth.Growth General Purpose Technologies Real Cost Reduction Total Factor Productivity.

Yeast vs. Mushrooms: A Note on Harberger's "A Vision of the Growth Process"

Harberger's "A Vision of the Growth Process", Presidential Address at the 1998 Annual Meeting of the American Economic Association, provides evidence that contributions to aggregate real cost reduction (RCR) are concentrated in a small number of industries. According to Harberger, this is because the effect of broad externalities - such as those linked to the growth of the total stock of knowledge or human capital, or brought about by economies of scale tied to the scale of the economy - is negligible as compared to industry- and firm-specific causes of productivity growth. The argument is that, if growth was driven mainly by broad externalities, contributions to aggregate RCR ought to be quite evenly distributed across sectors. Hence, the growth process looks more like "mushrooms" than "yeast". In this note, we argue that Harberger's evidence is not incompatible with the yeast vision. More specifically, we show that, if there is heterogeneity in the elasticities of sectoral total factor productivities (TFP) to shocks from other sectors, then concentration in the sectoral contributions to aggregate RCR can occur. But this is true even if sectoral TFP growth processes are completely driven by a broad externality stemming from a single sector. To the extent that the response of a sector's TFP to shocks from other sectors can be seen as a measure of absorptive capacity, we suggest that a realistic description of the growth process must go beyond the simple dichotomy "yeast vs. mushrooms", and take account of the intersectoral patterns of knowledge transfer.Growth, Real Cost Reduction, Total Factor Productivity, Absorptive Capacity

Fat-Tail Distributions and Business-Cycle Models

Recent empirical findings suggest that macroeconomic variables are seldom normally distributed. For example, the distributions of aggregate output growth-rate time series of many OECD countries are well approximated by symmetric exponential-power (EP) densities, with Laplace fat tails. In this work, we assess whether Real Business Cycle (RBC) and standard medium-scale New-Keynesian (NK) models are able to replicate this statistical regularity. We simulate both models drawing Gaussian- vs Laplace-distributed shocks and we explore the statistical properties of simulated time series. Our results cast doubts on whether RBC and NK models are able to provide a satisfactory representation of the transmission mechanisms linking exogenous shocks to macroeconomic dynamics.Growth-Rate Distributions, Normality, Fat Tails, Time Series, Exponential-Power Distributions, Laplace Distributions, DSGE Models, RBC Models

Fat-Tail Distributions and Business-Cycle Models

Recent empirical findings suggest that macroeconomic variables are seldom normally dis- tributed. For example, the distributions of aggregate output growth-rate time series of many OECD countries are well approximated by symmetric exponential-power (EP) den- sities, with Laplace fat tails. In this work, we assess whether Real Business Cycle (RBC) and standard medium-scale New-Keynesian (NK) models are able to replicate this sta- tistical regularity. We simulate both models drawing Gaussian- vs Laplace-distributed shocks and we explore the statistical properties of simulated time series. Our results cast doubts on whether RBC and NK models are able to provide a satisfactory representation of the transmission mechanisms linking exogenous shocks to macroeconomic dynamics.Growth-Rate Distributions, Normality, Fat Tails, Time Series, Exponential- Power Distributions, Laplace Distributions, DSGE Models, RBC Models.

Schumpeter Meeting Keynes: A Policy-Friendly Model of Endogenous Growth and Business Cycles

This paper studies an agent-based model that bridges Keynesian theories of demandgeneration and Schumpeterian theories of technology-fueled economic growth. We employ the model to investigate the properties of macroeconomic dynamics and the impact of public polices on supply, demand and the \fundamentals" of the economy. We find that the complementarities between factors in uencing aggregate demand and drivers of technological change affect both "short-run" fluctuations and long-term growth patterns. From a normative point of view, simulations show a corresponding complementarity between Keynesian and Schumpeterian policies in sustaining long-run growth paths characterized by mild fluctuations and acceptable unemployment levels. The matching or mismatching between innovative exploration of new technologies and the conditions of demand generation appear to suggest the presence of two distinct "regimes" of growth (or absence thereof) characterized by different short-run fluctuations and unemployment levels.Endogenous Growth, Business Cycles, Growth Policies, Business Cycle Policies, Evolutionary Economics, Agent-Based Computational Economics, Post-Walrasian Economics, Empirical Validation, Monte-Carlo Simulations

Are Business Cycles All Alike? A Bandpass Filter Analysis of Italian and US Cycles

In this paper, we apply the bandpass filter to the main Italian and US macroeconomic variables, we estimate cross-correlations with respect to a benchmark indicator of the business cycle, and we compare results with previous empirical analyses. The aim is to investigate on the existence of specific patterns and more general regularities, in order to provide further insights as to what facts macroeconomic theories are supposed to predict and explain, and new hints at the underlying generating mechanisms. Our results underline the existence of significant specificities of the Italian business cycle with respect to the US. Certain macroeconomic relations - such as those between consumption, investments, exports, stock market variables, and the real GDP - do not robustly hold. This is a clear signal that which variables prompt and which respond to business cycles depends on country- specific characteristics.Business Cycles, Bandpass Filter, Cross Correlations, Italian Economy, Macroeconomics.

Fat-tail Distributions and Business-Cycle Models

Recent empirical findings suggest that macroeconomic variables are seldom normally dis- tributed. For example, the distributions of aggregate output growth-rate time series of many OECD countries are well approximated by symmetric exponential-power (EP) den- sities, with Laplace fat tails. In this work, we assess whether Real Business Cycle (RBC) and standard medium-scale New-Keynesian (NK) models are able to replicate this sta- tistical regularity. We simulate both models drawing Gaussian- vs Laplace-distributed shocks and we explore the statistical properties of simulated time series. Our results cast doubts on whether RBC and NK models are able to provide a satisfactory representation of the transmission mechanisms linking exogenous shocks to macroeconomic dynamics.Growth-Rate Distributions, Normality, Fat Tails, Time Series, Exponential- Power Distributions, Laplace Distributions, DSGE Models, RBC Models.