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This page is the canonical public methodology for the per-headline credibilityScore field on NewsItem (GET /api/news/v1/list-feed-digest, proto worldmonitor.news.v1.NewsItem.credibility_score). credibilityScore and importanceScore answer different questions. Mixing them is the flaw a sophisticated buyer finds first. A state-controlled outlet can score high on importance and low on credibility at the same time. That split is the product. The pipeline is automated. There is no human review queue. Quality comes from the curated source-tier table, the fail-closed propaganda-risk registry, and digest corroboration counts that already exist. Third-party bias/factuality ratings (AllSides, MBFC) are reserved and not currently applied.

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Inputs

Only inputs that bear on truthfulness enter the score. Severity, recency, and the diplomacy/flashpoint boost stay on importanceScore. Weights sum to 1.0. The implementation is shared/news-credibility.js (computeCredibilityScore). The digest writes the field after classification and corroboration, alongside — not instead of — importanceScore.

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Component Maps

Source tier maps to: Propaganda risk maps to: Unlisted sources default to unknown, not low. That fail-closed default is the same contract as the provenance badges. Independent corroboration uses the digest’s existing corroboration count (the larger of story-identity cluster size and entity-level corroboration), capped at five sources, with 20 points per source before the 0.20 weight. This is the same corroboration signal importanceScore already consumes; it is not a second clustering pass.

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High-Risk Cap

After the weighted sum is rounded and clamped to 0–100, a source whose propaganda risk is high is capped at 40. The cap is the acceptance gate for state media. An RT or TASS item can still pick up corroboration points when independent outlets also report the event, but it cannot look like a high-credibility wire. Reuters with no extra corroboration scores around 80; RT with none scores in the low 20s.

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What This Score Is Not

  • It is not a statement that the underlying event is false. A true event reported first by state media still has low source credibility until independent outlets corroborate it.
  • It is not AllSides or MBFC. Those ratings are out of scope until a dedicated ingest exists.
  • It is not used to sort the news list. Relevance sort remains importanceScore, then publication time. Credibility is displayed, not substituted for newsworthiness.
  • Same-ecosystem inflation remains a known limitation: five Russian state desks clustering on one headline still share one high-risk cap, but the corroboration count is the digest’s existing publisher-family signal, not a new independence classifier.

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Surfaces

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Source Files

  • Scorer: shared/news-credibility.js
  • Digest writer: server/worldmonitor/news/v1/list-feed-digest.ts
  • API contract: proto/worldmonitor/news/v1/news_item.proto
  • Provenance registry: shared/source-provenance.ts
  • Tier table: shared/source-tiers.json
  • News list render: src/components/news/source-provenance.ts, src/components/NewsPanel.ts
  • Pipeline sibling: News Digest and Briefing