A theoretical construct designed to analyse the behaviour of economic agents using quantitative and logical methods. A model can be formulated verbally and/or in the form of equations and/or diagrams, and is composed of a list of variables that characterize the economic agents and the economic environment under consideration, and a list of assumptions about their interaction. A model assigns objectives to economic agents and specifies constraints on choices. An economic model is always a simplified representation of the real world, and the choice of the degree of simplification is dictated by the focus of the research and the availability of relevant information. See also agent-based modelling; Arrow-Debreu economy; computable general equilibrium model; dynamic stochastic general equilibrium model; real business cycle.