Universe¶
The population a dataset describes.
Definition¶
A universe is the set of entities that a dataset covers. It answers the question: "Who or what is included in this data?"
Why it matters¶
Two datasets with different universes cannot be directly compared. If one survey covers "all adults" and another covers "working-age adults", their employment rates describe different populations.
Invariant requires explicit universe declarations so it can detect when comparisons cross universe boundaries.
Common confusions¶
"Can't I just document this in a footnote?"
You can, but users will ignore it. Invariant makes the constraint enforceable.
"What if universes partially overlap?"
Invariant supports partial comparability with required acknowledgment. The comparison can proceed, but with disclosed caveats.
Minimal example¶
Universe(
id=UniverseId.create(),
name="Working-age adults",
description="Persons aged 18-64, excluding institutionalized population"
)