Sander van der Hoog

EURACE: A Massively Parallel Agent-Based Model of the European Economy ⋆

EURACE is a major European attempt to construct an agent-based model of the European economy with a very large population of autonomous, purposive agents interacting in a complicated economic environment. To create it, major advances are needed, in particular in terms of economic modeling and software engineering. In this paper, we describe the general structure of the economic model developed for EURACE and present the Flexible Large-scale Agent Modeling Environment (FLAME) that will be used to describe the agents and run the model on massively parallel supercomputers. Illustrative simulations with a simplified model based on EURACE’s labor market module are presented.

The Eurace@Unibi Model: An Agent-Based Macroeconomic Model for Economic Policy Analysis

This document provides a description of the modeling assumptions and economic features of the Eurace@Unibi model. Furthermore, the document shows typical patterns of the output generated by this model and compares it to empirically observable stylized facts. The Eurace@Unibi model provides a representation of a closed macroeconomic model with spatial structure. The main objective is to provide a micro-founded macroeconomic model that can be used as a unified framework for policy analysis in different economic policy areas and for the examination of generic macroeconomic research questions. In spite of this general agenda the model has been constructed with certain specific research questions in mind and therefore certain parts of the model, e.g. the mechanisms driving technological change, have been worked out in more detail than others. The purpose of this document is to give an overview over the model itself and its features rather than discussing how insights into particular economic issues can be obtained using the Eurace@Unibi model. The model has been designed as a framework for economic analysis in various domains of economics. A number of economic issues have been examined using (prior versions of) the model (see Dawid et al. (2008), Dawid et al. (2009), Dawid et al. (2011a), Dawid and Harting (2011), van der Hoog and Deissenberg (2011), Cincotti et al. (2010)) and recent extensions of the model have substantially extended its applicability in various economic policy domains, however results of such policy analyses will be reported elsewhere. Whereas the overall modeling approach, the different modeling choices and the economic rationale behind these choices is discussed in some detail in this document, no detailed description of the implementation is given. Such a detailed documentation is provided in the accompanying document Dawid et al. (2011b).

Describing economic agent-based models – Dahlem ABM documentation guidelines

At the 100th Dahlem conference “New Approaches in Economics after the Financial Crisis” a working group devised guidelines for the documentation of computational economic agent-based models, based upon – but differing from – the ODD protocol Grimm et al. (2006, 2010). This paper sketches the motivation for coming up with a new set of guidelines tailored to economic multi-agent modelling, and presents these. While analytical economic models can often be precisely and concisely stated by a few equations together with an economic interpretation of their elements, a computational agentbased model, as a conceptual piece of work, may not always be a very tangible entity. For example, it is represented by but usually not identical to the (many) equations constituting the computer code. It is therefore not always easy to describe the model in a way that provides the reader with a thorough understanding of the model. The present guidelines are an attempt at standardizing such descriptions to support understanding and communication, as well as the comparability of economic multi-agent models.

Production and Finance in EURACE

EURACE is a major FP6 STREP project aiming at constructing anexhaustive agent-based model of the European economy, populated by avery large number of sophisticated, autonomous agents. The EURACEmodel, which has an explicit spatial structure, includes all the majormarkets considered in quantitative macroeconomic modelling (consumergoods, investment goods, labour, credit and finance). It offers aunique opportunity for studying, from a new perspective, theempirically observed but theoretically poorly understood link betweenthe real and the financial sphere of a modern economy. After summarilypresenting the main features of EURACE, this paper describes in moredetail the newly developed financial management module thatintermediates between the real and the financial spheres in EURACE. Ina nutshell, this module defines the link between the hiring andinvestment behavior of the firms as a function of the revenues theyobtain by selling their products, of the money they can raise on thecredit and financial markets, of their dividend policy, and othermajor aspects of financial decision-making.

Bubbles, Crashes and the Financial Cycle: Insights from a Stock-Flow Consistent Agent-Based Macroeconomic Model

This paper explores how different credit market and banking regulations affect business fluctuations. Capital adequacy and reserve requirements are analysed for their effect on the risk of severe downturns. We develop an agent-based macroeconomic model in which financial contagion is transmitted through balance sheets in an endogenous firm-bank network, that incorporates firm bankruptcy and heterogeneity among banks to capture the fact that contagion effects are bank-specific. Using concepts from the empirical literature to identify amplitude and duration of recessions and expansions we show that more stringent liquidity regulations are best to dampen output fluctuations and prevent severe downturns. Under such regulations both leverage along expansions and amplitude of recessions become smaller. More stringent capital requirements induce larger output fluctuations and lead to deeper, more fragile recessions. This indicates that the capital adequacy requirement is pro-cyclical and therefore not advisable as a measure to prevent financial contagion.

Bubbles, Crashes and the Financial Cycle: The Impact of Banking Regulation on Deep Recessions

This paper explores how different credit market- and banking regulations affect business fluctuations. Capital adequacy- and reserve requirements are analysed for their effect on the risk of severe downturns. We develop an agent-based macroeconomic model in which financial contagion is transmitted through balance sheets in an endogenous firm-bank network, that incorporates firm bankruptcy and heterogeneity among banks to capture the fact that contagion effects are bank-specific. Using concepts from the empirical literature to identify amplitude and duration of recessions and expansions we show that more stringent liquidity regulations are best to dampen output fluctuations and prevent severe downturns. Under such regulations both leverage along expansions and amplitude of recessions become smaller. More stringent capital requirements induce larger output fluctuations and lead to deeper, more fragile recessions. This indicates that the capital adequacy requirement is pro-cyclical and therefore not advisable as a measure to prevent financial contagion.

A Heterogeneous Agent Macroeconomic Model for Policy Evaluation: Improving Transparency and Reproducibility

This paper provides a detailed description of the Eurace@Unibi model, which has been developed as a versatile tool for economic policy analysis. The model explicitly incorporates the decentralized interaction of heterogeneous agents across different sectors and regions. The modeling of individual behavior is based on heuristics with empirical microfoundations. Although Eurace@Unibi has been applied successfully to different policy domains, the complexity of the structure of the model, which is similar to other agent-based macroeconomic models, has given rise to concerns about the reproducibility and robustness of the obtained insights. This paper addresses these concerns by describing the exact details of all decision rules, interaction protocols and balance sheets used in the model. Furthermore, we discuss the use of a virtual appliance as a tool allowing third parties to reproduce and verify the simulation results. The paper provides a systematic and extensive sensitivity analysis of the simulation output with respect to a set of key parameters. Particular emphasis is put on the question which parameter constellations give rise to strong economic fluctuations and high frequencies of sudden downturns in economic activity.

Energy Shocks and Macroeconomic Stabilization Policies in an Agent-Based Macro Model

In this chapter we consider the effects of exogenous energy shocks on an agent-based macroeconomic system and study the out-of-equilibrium dynamics. We introduce automatic stabilizers that allow the artificial economy to absorbe the shocks. Two types of macroeconomic stabilization policies are implemented: a consumer subsidy scheme that compensates households for their loss in purchasing power, and a tax reduction scheme that affects both households and firms to support consumption and investments. Policy experiments are then carried out to evaluate the effectiveness of these macroeconomic policies. Finally, we are able to distinguish between short- and long-term effects of the policy measures.

Deep Learning in Agent-Based Models: A Prospectus

A very timely issue for economic agent-based models (ABMs) is their empirical estimation. This paper describes a line of research that could resolve the issue by using machine learning techniques, using multi-layer artificial neural networks (ANNs), or so called Deep Nets. The seminal contribution by Hinton et. al. (2006) introduced a fast and efficient training algorithm called Deep Learning and there have been major breakthroughs in machine learning ever since. Economics has not yet benefited from these developments, and therefore we believe that now is the right time to apply Deep Learning and multi-layered neural networks to agent-based models in economics.