Understanding Scenarios

What is a scenario?

A scenario is a named run: one data set per input variable, a projection period (or model horizon), and any fine-tuning. ScenarioPulse lets you run several and plot them together on one chart — the “fan of forecasts” — to see how different assumptions drive different outcomes.

There are four kinds, one per modeling stage — Demography, Macro, Pension Coverage, and Pension Finance — each with its own scenario list, and later stages build on pinned scenarios from earlier ones. See how the model works for the full pipeline, how to model demography and how to model pensions for walkthroughs, and the demographic data model for the full demography reference.

What a Demography scenario is made of

Input	Description
Country	Selects the catalog of data sets and the baseline.
Projection period	Start from year and Forecast N years → horizon (with a confidence badge).
Population	Start-of-projection age–sex structure (data-set dropdown).
Fertility / Mortality / Migration	A data set plus an optional trend (±X%/yr for N years, then plateau). Migration also offers preset time paths.
Scenario name	Auto-named per country (ES_v1, RU_v2, …); editable.

Each country opens on its baseline — the official reference data and assumptions (for Spain, calibrated to the INE projection). The first Add scenario therefore gives a credible reference line.

Macro, Pension Coverage, and Pension Finance scenarios follow the same “data set + fine-tuning + name” shape, with their own inputs — see how to model pensions.

The fan chart

Each Add scenario adds a line to the chart and an entry to the Scenarios list, with a table of each scenario’s data set, horizon and adjustments. You can:

• Show/hide a scenario with the checkbox next to its name.
• Load its settings back into the form to tweak.
• Save it to your account (sign-in required) and share a public link.
• Del to remove it.

Scenarios accumulate until removed. Signed out, they live in your browser’s localStorage and migrate to your account when you sign up.

The demographic projection method

Starting from a base-year population (age × sex), the engine projects year by year: each cohort ages and survives by mortality (qx), births are added from fertility, and net migration is applied. Fertility, mortality and migration can follow a “trend then plateau” path. Isolating one assumption while holding the rest fixed shows its effect — exactly what the fan chart visualizes.

Coverage and Finance chain their own projections on top of this one — see how the model works for the full pipeline.