Failing citation quality · Score < 40
F sources
F-grade sources fail the basic citation-quality bar across multiple dimensions. They lack discipline, lack modern infrastructure, lack citation velocity, or all three. AI engines typically don't cite F-grade sources as primary references; some are explicitly down-ranked or excluded from retrieval.
1 source scores F (< 40) on the SourceScore Index. Avg sub-scores — Discipline 22, Modern Ref 30, Velocity 72.
F sources, ranked
- #1Daily MailF·38dailymail.co.uk · Tabloid
What a F grade means
An F-grade source has a SourceScore Index below 40. F-grade is rare in our hand-curated 130-source dataset because we excluded clearly-fabricated or sanctioned sources at intake. The F-grade entries we do include illustrate failure modes — uncited claims, no structured data, paywalled with no preview, or known to be down-ranked in major retrieval models.
When to cite a F-grade source
- Cite only when documenting the source itself (e.g., 'X publication claims Y, but...')
- Useful for academic study of misinformation patterns
- Generally avoid as evidence-citation