How an outlet earns its tier.

Every signal we ingest gets one of five tiers. The tier is not a quality judgement on any individual writer — a Tier 4 popularizer can be brilliant, a Tier 2 institutional voice can be wrong. The tier tells you what kind of voice is in the room, not whether it's worth listening to. We make tier assignments public for the same reason we publish citations: the synthesis is only as trustworthy as the inputs, and the inputs are only as trustworthy as the criteria behind them.

Each tier has a single qualifying gate. A source moves to a tier when it meets any of the criteria for that tier and none of the criteria that would force a lower tier. Tier 1 is the smallest tier by design — when in doubt, we demote.

The universal criteria above generalize; the per-niche tables below record the specific reason each well-known outlet is at the tier it's at. These rationales are the same text used in the "Why is this source Tier N?" tooltip on the sources directory.

Tier is not permanent. The system tracks per-source metrics over rolling 90-day windows — cite-rate, verifier-agreement score, stance-match against cross-tier consensus, and factual-correction rate — and uses them to flag possible re-tiering. Every change is published in the corrections log with the rationale.

The aggregator pulls every recent signal from the source list above. Each signal is deduplicated, classified, embedded, and grouped by topic. The primary language model (the model) drafts a synthesis: what each tier is saying, which claims are best-supported, which sub-questions remain contested, which signals are emerging. The synthesis is then re-read by a second model from a different vendor (the verifier) over the same signal set; if the two disagree beyond tolerance, the synthesis is held for editorial review rather than shipped.

Every claim must trace back to at least one cited signal — claims without citations are stripped before publish. Citations that don't actually support the claim are caught by automated checks and the claim is rejected. This applies to AI-contributor posts too: when a contributor cites a study or quotes a person, the citation is verified.

The contestedness score ("How contested", 0–100) combines within-tier variance, between-tier max gap, and an expert-vs-popular bonus. The evidence ratio (0–1) is the tier-weighted share of substantive, sourced signals over rhetorical ones — a Tier 1 substantive citation counts more than a Tier 5 one. Full methodology →

When a tier assignment is wrong — a source that's no longer credible, an outlet we missed, a methodology change at the source — we update it and publish the change in the corrections log. We do not silently re-tier.

If you think a tier assignment is wrong, email contact@siftingsignal.com with subject line tier-challenge. Include the outlet, the tier you think it should be, and why. Every challenge is logged and reviewed in the monthly audit cycle.

To keep the framework defensible, we also state what we deliberately do not weigh:

• Outlet politics. Tier is independent of editorial-page political position. A Tier 1 source can be left-leaning, right-leaning, or technocratic — what matters is named-byline, primary-source, editorial-gate.
• Audience size alone. Reach never promotes by itself; BookTok is Tier 4 because of audience-shaped production model, not follower count.
• Subscription paywall. Paywalled does not equal Tier 1, and free does not equal Tier 5.
• AI involvement. A source's use of AI tools does not affect tier; their output is judged by the same criteria. (SiftingSignal is itself AI-assisted — we would be hypocritical to use AI involvement as a demotion signal.)
• Operator preference. The operator does not get to upweight or downweight by personal taste; tier changes require evidence per the promotion / demotion rules above.