8. Macroeconomic fluctuations and heterogeneous agents (original) (raw)

Heterogeneous Enterprises in a Macroeconomic Agent-Based Model

We present a macroeconomic agent-based model that combines several mechanisms operating at the same timescale, while remaining mathematically tractable. It comprises enterprises and workers who compete in a job market and a commodity goods market. The model is stock-flow consistent; a bank lends money charging interest rates, and keeps track of equities. Important features of the model are heterogeneity of enterprises, existence of bankruptcies and creation of new enterprises, as well as productivity increase. The model's evolution reproduces empirically found regularities for firm size and growth rate distributions. It combines probabilistic elements and deterministic dynamics, with relative weights that may be modified according to the considered problem or the belief of the modeler. We discuss statistical regularities on enterprises, the origin and the amplitude of endogeneous fluctuations of the system's steady state, as well as the role of the interest rate and the cred...

Microeconomic Structure determines Macroeconomic Dynamics. Aoki defeats the Representative Agent

Masanao Aoki developed a new methodology for a basic problem of economics: deducing rigorously the macroeconomic dynamics as emerging from the interactions of many individual agents. This includes deduction of the fractal / intermittent fluctuations of macroeconomic quantities from the granularity of the mezo-economic collective objects (large individual wealth, highly productive geographical locations, emergent technologies, emergent economic sectors) in which the micro-economic agents self-organize.

E Pluribus Unum: Macroeconomic modelling for multi-agent economies

Journal of Economic Dynamics and Control, 2013

From the point of view of the average macroeconomist, agent based modelling has an obivious drawback: It makes impossible to think in aggregate terms. The modeller, in fact, can reconstruct aggregate variables only "from the bottom up" by summing the individual quantities. As a consequence the interpretation of the trasmission mechanism of shocks is somehow arbitrary. We propose a modelling strategy which reduces the dimensionality of an agent based framework by replacing the actual distributional features (in our model: the distribution of …rms'…nancial conditions) with the …rst and second moments of the distribution itself. The main message is that the di¢ culty of thinking in macroeconomic terms when dealing with multi-agent economies can be circumvented by means of an appropriate aggregation procedure -which we label the Modi…ed-Representative Agent -such that the distribution of agents'characteristics can be approximated by (at least) the (…rst and second) moments of the distribution. The moments of the distribution play the role of macroeconomic variables.

Chapter 23 Heterogeneous Agent Models in Economics and Finance

Handbook of Computational Economics, 2006

This chapter surveys work on dynamic heterogeneous agent models (HAMs) in economics and finance. Emphasis is given to simple models that, at least to some extent, are tractable by analytic methods in combination with computational tools. Most of these models are behavioral models with boundedly rational agents using different heuristics or rule of thumb strategies that may not be perfect,

Heterogeneity in Economics

Journal of Economic Interaction and Coordination, 2006

This paper argues that heterogeneity of agents’ characteristics plays a fundamental role in the economy and should do so in economic models. Three aspects are considered. Firstly the notion that assuming heterogeneity was a solution to the problem posed by the results of Sonnenschein Mantel and Debreu is considered and it is suggested that the more pragmatic approach adopted by Hildenbrand is likely to be more productive. Next the role of adaptation and evolution which necessarily involve variety or heterogeneity is examined. It is suggested that heterogeneity will persist since agents will only slowly learn to adapt and that in the meantime the environment will change. Lastly the role of heterogeneity in financial markets is examined. It is suggested that heterogeneous and varying expectations may account for many of the stylised facts which do not seem to be consistent with the standard financial markets model.

Aggregation of Heterogeneous Interacting Agents: The Variant Representative Agent Framework

Journal of Economic Interaction and Coordination, 2006

In this paper we have presented a variant of the stochastic aggregation approach which basically consists in exploring the evolution over time of higher moments of the economic units' distribution. In a sense therefore, we propose to focus on the behavior of a Variant Representative Agent. An application to a classical growth model shows that changes in aggregate output usually associated with Total Factor Productivity in the aggregative interpretation of the framework may be due to changes in the distribution of agents in terms of capital intensity. The application to a model by Gatti et al. (Interaction and market structure, Springer, 2000) shows the efficacy of the method in capturing the evolution over time of the distribution of firms in terms of financial solidity (equity ratio). The method seems general enough to cover a wide range of economic situations in which heterogeneity is relevant and persistent. It seems also simple enough to deserve the attention of the macroeconomist dissatisfied with the RA who wants to derive meaningful and microfounded macroeconomic results.