Modelling workflow

Practitioner workflow

All bundled families expose the same modelling idea:

choose a model
    ↓
solve benchmark
    ↓
create policy scenario
    ↓
apply economic shock / named scenario
    ↓
solve counterfactual
    ↓
inspect and compare results

For the Hosoe Simple, Hosoe Standard, and CAMCGE families this is implemented by the generic v0.8 workflow:

model façade
    ↓
protected Equilibrium
    ↓
independent Scenario
    ↓
Result snapshot

Example:

from cge_core import StandardCGE

base = StandardCGE.example().solve()

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

result = scenario.solve()
result.compare(base)

IFPRI keeps the same practitioner sequence through model-specific types and named scenarios:

from cge_core import IFPRICGE

base = IFPRICGE.synthetic().solve()
result = base.scenario("TARCUT1").solve()

Internally this path uses IFPRIEquilibrium, IFPRIScenario, and IFPRIResult plus the IFPRI calibration and closure machinery. It is intentionally separate from the generic CGE / CoreEngine path.

Why solve the benchmark first?

Calibration reconstructs model parameters and verifies that the benchmark data are consistent with the model’s equilibrium structure. The benchmark is therefore the reference state against which a counterfactual is interpreted.

Why is a generic scenario a clone?

For SimpleCGE, StandardCGE, and CamCGE, a policy experiment must not mutate the benchmark or another policy experiment. v0.8 therefore creates one independent concrete model clone per generic scenario. Multiple counterfactuals can coexist.

IFPRI instead constructs its named scenario model through the IFPRI-specific scenario builder using the benchmark dataset and calibration. The user-facing economic idea is the same even though the internal mechanism differs.

Closure

Closure is model-owned, not a universal framework default.

• SimpleCGE, StandardCGE, and CamCGE declare canonical closure metadata through their model configuration and ModelSpec.

• IFPRICGE retains IFPRI-specific macro closure and named scenario machinery.

This removes routine numeraire and redundant-equation bookkeeping from ordinary user code without pretending closure is economically unimportant.

Advanced users can still work through lower-level or model-specific APIs when closure itself is the object of research.

Results

For the generic Simple/Standard/CAMCGE path, Result is an immutable numerical snapshot of a successful solve. Use value(), summary(), and compare() for ordinary analysis. .raw is available when direct Pyomo access is genuinely needed.

IFPRI provides corresponding IFPRIResult methods over its model-specific solved state.