Measure the assumptions.
Don't confuse them with history.

Compare the frozen engine 0.3.6 and revised engine 0.3.7 with the same policies and random seeds. See modeled wages, inflation, and financing alongside properly labeled public reference figures. Neither engine is a verified forecast.

Data definitions matter. BLS values below are 2025 metropolitan-area unemployment averages. They are not 2026 city-proper figures. The Federal Reserve’s 2% PCE figure is a national long-run policy target, not an observed city inflation rate.

Ready. Runs are read-only and never touch saved games.

REFERENCE & SIMULATED OUTCOME

Results

Observed 2025 BLS unemployment—

Federal Reserve long-run PCE objective2.0%

National target, not local actual inflation.

New engine / old engine0.3.7 / 0.3.6

Same start and seeds, independently replayed.

Policy preset	GDP before	GDP after	GDP Δ	Unemployment after	Modeled inflation	Real wage index	Financing rate

Comparison by economic policy

Model outputs, not actual city history or historical fit.

Measure

Important limitations

Historical Backtesting is available in v2.2: loading observed year-by-year economic data, comparing reality to a counterfactual simulated run, and displaying provenance. Open Historical Lab to add sourced observations and compare synthetic trajectories; the calibration page itself does not reconstruct past cities.

Measure the assumptions.Don't confuse them with history.

Results

Comparison by economic policy

Important limitations

Measure the assumptions.
Don't confuse them with history.