Ineconomics, anagent is an actor (more specifically, adecision maker) in amodel of some aspect of theeconomy. Typically, every agent makes decisions by solving a well- or ill-definedoptimization or choice problem.
For example,buyers (consumers) andsellers (producers) are two common types of agents inpartial equilibrium models of a singlemarket.Macroeconomic models, especiallydynamic stochastic general equilibrium models that are explicitly based onmicrofoundations, often distinguishhouseholds,firms, andgovernments orcentral banks 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, asworkers, and as voters in the model. Some macroeconomic models distinguish even more types of agents, such as workers and shoppers[1] orcommercial banks.[2]
The termagent is also used in relation toprincipal–agent models; in this case, it refers specifically to someone delegated to act on behalf of aprincipal.[3]
Inagent-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.[4] The concept of anagent 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.
Aneconomic model in which all agents of a given type (such as all consumers, or all firms) are assumed to be exactly identical is called arepresentative agent model. A model which recognizes differences among agents is called aheterogeneous 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.[5] For example, considering heterogeneity in age is likely to be necessary in a model used to study the economic effects of pensions;[6] considering heterogeneity in wealth is likely to be necessary in a model used to studyprecautionary saving[7] or redistributive taxation.[8]