Computable General Equilibrium
Also known as: CGE Model, Applied General Equilibrium, AGE Model, Walrasian Simulation Model
A computable general equilibrium (CGE) model is a numerical simulation of an entire economy in which optimizing producers and consumers interact through markets that all clear simultaneously. Building on Walras's general-equilibrium theory and a benchmark social accounting matrix, a CGE model is calibrated to reproduce a base-year economy and then solved for the new vector of prices and quantities that would prevail under a counterfactual policy — a tax reform, a tariff change, a carbon price — capturing how the shock reverberates and re-equilibrates across every market.
Key highlights
- Captures economy-wide price responses, input and consumption substitution, and feedback effects that fixed-coefficient input-output and SAM models cannot.
- Grounded in explicit microeconomic optimization, giving internally consistent, theory-based welfare measures.
- Calibrated to a benchmark SAM so it reproduces the observed economy exactly before any shock is applied.
- Flexible and modular: can incorporate multiple regions, sectors, household types, taxes, trade, and environmental accounts for a wide range of policy questions.
Intuition
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How it works
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When to use it
Use a CGE model when a policy or shock has economy-wide ramifications that work through prices and resource reallocation — tax and trade reforms, climate and energy policy, large structural changes — and when partial-equilibrium or fixed-coefficient input-output analysis would miss the substitution, income, and feedback effects. CGE models require a balanced benchmark SAM and credible elasticity estimates, and they assume optimizing behavior, well-defined market clearing, and (in the standard form) competitive markets. They are best for comparing equilibria under alternative policies rather than for short-run forecasting, and their results are conditional on the chosen functional forms, elasticities, and closure rules, which should always be subjected to sensitivity analysis.
Strengths & limitations
- Captures economy-wide price responses, input and consumption substitution, and feedback effects that fixed-coefficient input-output and SAM models cannot.
- Grounded in explicit microeconomic optimization, giving internally consistent, theory-based welfare measures.
- Calibrated to a benchmark SAM so it reproduces the observed economy exactly before any shock is applied.
- Flexible and modular: can incorporate multiple regions, sectors, household types, taxes, trade, and environmental accounts for a wide range of policy questions.
- Calibration fixes most parameters from a single benchmark year and borrowed elasticities rather than estimating them, so results inherit those assumptions.
- Outcomes are sensitive to functional-form choices, elasticity values, and the macroeconomic closure rule, sometimes more than to the policy itself.
- Standard models assume competitive markets, optimizing agents, and an existing equilibrium, which may misrepresent imperfect competition, unemployment, or disequilibrium dynamics.
- Complexity and limited transparency can make results hard to communicate and validate, and standard CGE models report point estimates without statistical confidence intervals.
Common pitfalls
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Applications
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Frequently asked
How does a CGE model differ from an input-output or SAM multiplier model?
Input-output and SAM multiplier models are linear, demand-driven, and price-free: output responds proportionally to final demand with fixed coefficients. A CGE model uses the same SAM as its benchmark database but adds optimizing producers and consumers, flexible substitution, and market-clearing prices, so a shock triggers price changes and resource reallocation. The trade-off is that CGE requires elasticity assumptions and is harder to validate, while input-output is transparent but ignores prices and substitution.
What is calibration and why is it used instead of estimation?
Calibration sets a model's free parameters so it exactly reproduces the benchmark social accounting matrix as an equilibrium at base-year prices, with elasticities drawn from the literature. It is used because a full CGE model has far more parameters than a single cross-section of data could identify econometrically. The cost is that the model's behavior rests on assumed elasticities and one benchmark year, which is why sensitivity analysis over those values is essential.
What is a 'closure rule' in a CGE model?
A closure rule specifies which macroeconomic variables are fixed (exogenous) and which adjust (endogenous) to balance the model — for example whether investment is savings-driven or savings adjust to investment, whether the labor market clears at full employment or wages are fixed, and how the government balance closes. Because these choices determine which adjustment margins absorb a shock, the chosen closure can substantially change the sign and size of the simulated welfare effect, so it must be stated and tested.
Sources
- 1.Shoven, J. B., & Whalley, J. (1992). Applying General Equilibrium. Cambridge Surveys of Economic Literature. Cambridge University Press.ISBN 9780521319867
- 2.Shoven, J. B., & Whalley, J. (1984). Applied general-equilibrium models of taxation and international trade: An introduction and survey. Journal of Economic Literature, 22(3), 1007–1051.
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ScholarGate. (2026, June 22). Computable General Equilibrium. ScholarGate. https://scholargate.app/economics/computable-general-equilibrium