Narrative to numbers

A story without numbers is a fairy tale. It cannot be wrong, so it cannot be tested, and it never tells you what price to pay. Numbers without a story are a spreadsheet nobody believes. Every input came from somewhere, but nobody can say where, so any reader who disagrees has nothing to argue with except the answer.

The bridge between them is a mapping rule, and it runs both ways:

• Every claim in the story moves exactly one driver in the model.
• Every input in the model carries one sentence of story.

Two counts prove the bridge holds. Model inputs with no story sentence: zero. Story claims with no driver: zero. Both counts are mechanical, and the second one is where most valuations fail — a claim that moves no driver is decoration, and a claim that moves two is double counted.