In economics, an agent is an actor (more specifically, a decision maker) in a

model A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure. Models c ...

of some aspect of the economy. Typically, every agent makes decisions by solving a well- or ill-defined optimization or choice problem. For example, ''buyers'' ( consumers) and ''sellers'' ( producers) are two common types of agents in

partial equilibrium In economics, partial equilibrium is a condition of economic equilibrium which analyzes only a single market, ''ceteris paribus'' (everything else remaining constant) except for the one change at a time being analyzed. In general equilibrium ana ...

models of a single market. Macroeconomic models, especially dynamic stochastic general equilibrium models that are explicitly based on

microfoundations Microfoundations are an effort to understand macroeconomic phenomena in terms of economic agents' behaviors and their interactions.Maarten Janssen (2008),Microfoundations, in ''The New Palgrave Dictionary of Economics'', 2nd ed. Research in microf ...

, often distinguish households,

firm A company, abbreviated as co., is a legal entity representing an association of people, whether natural, legal or a mixture of both, with a specific objective. Company members share a common purpose and unite to achieve specific, declared go ...

s, and governments or

central bank A central bank, reserve bank, or monetary authority is an institution that manages the currency and monetary policy of a country or monetary union, and oversees their commercial banking system. In contrast to a commercial bank, a central ba ...

s as the main types of agents in the economy. Each of these agents may play multiple roles in the economy; households, for example, might act as consumers, as workers, and as voters in the model. Some macroeconomic models distinguish even more types of agents, such as workers and shoppers or commercial banks. The term ''agent'' is also used in relation to principal–agent models; in this case, it refers specifically to someone delegated to act on behalf of a principal. In agent-based computational economics, corresponding agents are "computational objects modeled as interacting according to rules" over space and time, not real people. The rules are formulated to model behavior and social interactions based on stipulated incentives and information. The concept of an ''agent'' may be broadly interpreted to be any persistent individual, social, biological, or physical entity interacting with other such entities in the context of a dynamic multi-agent economic system.

Representative vs. heterogenous agents

An economic model in which all agents of a given type (such as all consumers, or all firms) are assumed to be exactly identical is called a representative agent model. A model which recognizes differences among agents is called a heterogeneous agent model. Economists often use representative agent models when they want to describe the economy in the simplest terms possible. In contrast, they may be obliged to use heterogeneous agent models when differences among agents are directly relevant for the question at hand. For example, considering heterogeneity in age is likely to be necessary in a model used to study the economic effects of pensions; considering heterogeneity in wealth is likely to be necessary in a model used to study precautionary saving or redistributive taxation.

Representative vs. heterogenous agents

See also

References

Further reading