How well we know a date — verified, corroborated, or compiled — printed on every row.
Every date in this corpus carries a grade for how well it is evidenced. Verified means checked against a primary source: a gazette, a statute, a central bank notice. Corroborated means two or more INDEPENDENT secondary sources agree. Compiled means one source, or one we could not independently confirm.
Most of the corpus is compiled, and saying so is the point of the label. A dataset that grades nothing is claiming uniform confidence it cannot have, and the reader discovers the variation the expensive way.
The word doing the work is INDEPENDENT. An aggregator agreeing with our own research is one piece of evidence wearing two hats. Two newspapers reprinting one wire story are one source. That is why the corroborated tier is small and why it means something.
Assurance is about our sourcing — how well we know it. Precision is about the date itself — how exactly it is fixed. A date can be poorly evidenced and exact, or well evidenced and approximate.
See also precision · edition · jurisdiction
Filter to what has been confirmed against an authority with min_assurance=verified. See what we hold.