Evidence levels
Every statement on this site carries one of five levels. A level describes the sources behind a statement. It does not say how likely the statement is to be true.
How a level is set
- A level can never be higher than the best source behind the statement. A retailer page supports hobby consensus at most. A specialist checklist supports expert source. Peer-reviewed needs a published paper or a monograph.
- Hobby consensus needs two independent origins. Two sellers who copy each other count once.
- A statement that rests on one seller or one keeper is anecdotal. Treat it as a lead.
- Where a statement mixes sources, the weakest source sets the level shown on the page.
Unchecked
An Unchecked statement has a source and a place in it, but a person has not yet compared the statement with that place. It is a draft. Read the source if the statement matters to you.
Unknown
Where nobody has tested something, the page says Unknown and links the open question. A gap is useful information. It tells researchers and keepers where a record would help most. See the open questions.
Standing of a source
The evidence level is about what a source can support. The standing of a source is about whether the reference itself is right. We check authors, titles and years against Crossref, DataCite and Open Library, and we open web pages to see that they still load.
Every source has its own page that lists what it is used for. Browse the sources.