Your first policy simulation

A CGE counterfactual asks:

If the exogenous policy or environment changed, what internally consistent equilibrium would satisfy the model afterward?

Start from a solved benchmark:

from cge_core import StandardCGE

base = StandardCGE.example().solve()

Create an independent scenario and change an economic assumption:

policy = base.scenario("Tariff cut")
policy.tariff("BRD", change=-0.50)

change=-0.50 means “reduce the existing tariff rate by 50 percent.” It does not mean “subtract 50 percentage points.”

Solve the new equilibrium:

result = policy.solve()

Compare all endogenous variables with the benchmark:

comparison = result.compare(base)
comparison

The resulting differences reflect all model adjustments together: domestic and import prices, production, trade, factor allocation, income, demand, saving, and other endogenous quantities respond jointly.

For a second independent experiment:

factor_case = base.scenario("More capital")
factor_case.endowment("CAP", change=0.10)
factor_result = factor_case.solve()

The two scenarios do not share mutable counterfactual state.