The words the model actually uses

Terms

Ensemble

The set of futures a single run produces. Each one starts from the same world and meets a different sequence of shocks and a different draw of the uncertain coefficients. 250 is the default.

Path

One future inside the ensemble. A path is a complete run of the model from the base year to the horizon.

Seed

The number that fixes which shocks happen in which years. Two scenarios run on the same seed meet identical luck, so the difference between them is your lever rather than the noise.

Common random numbers

The technique behind that. Each random draw is addressed by the year, the country and the channel it belongs to rather than pulled in sequence, so adding a lever cannot shift the luck of everything after it.

Branch

A cluster of paths that ended up in a similar place. Each branch is reported with the share of the ensemble that landed in it, which is the closest thing here to a probability.

Horizon

How many years forward a run goes. Longer horizons are not more knowledge, they are more compounding of the same assumptions, and the confidence panel says so.

Lever

A change you make to the world. 27 of them, from a tariff on one pair of countries to a worldwide carbon price. Each has a start year, a duration and a phase in.

Coalition

A group acting as one. A lever imposed by the G7, the EU or NATO applies from every member at once, and the load on the target is weighted by the share of world output imposing it.

Channel

The route a shock travels: trade, energy, money, people, capability, alignment, inputs. The causes panel is organised by channel.

Contribution

A named term inside a headline number. Growth is built as the sum of eleven of them, inflation nine, unemployment five. They add up exactly, which is what makes the drill down honest.

Provenance

What kind of number a data point is. Curated means entered by hand from a source. Partial means some fields were. Patterned means inferred from region, income tier and structure. Sourced means pulled from the World Bank with its year attached.

Potential output

What an economy could produce at full employment. The gap between actual and potential drives inflation and unemployment, and closes slowly through hysteresis.

Gravity trade

The model of who trades with whom: bigger economies closer together trade more. Each country keeps its top partners and the weights are renormalised, which is what makes 238 countries run in seconds.

Sensitivity

How much the answer moves when one uncertain parameter moves. The confidence panel ranks the parameters by how much of the spread each one is responsible for.

Analogue

A historical episode scored against your run on nine features. Not a claim that history repeats, a way to ask whether the model has put you somewhere that has happened before.