GAP — no independent or primary evidence that schema markup ITSELF improves AI-answer citation; vendor claims (FAQ schema → 2.8× citations, author schema → 3×) are single-source and unverified

Gap: There is no independent or primary evidence that schema markup ITSELF improves AI-answer citation. Google's own documentation says structured data confers rich-result eligibility, not ranking (Google documentation — structured data makes pages ELIGIBLE for rich results, NOT a generic ranking boost ("enables a feature to be present, does not guarantee that it will be present")). The peer-reviewed GEO lift came from body-text edits, not markup (GEO paper — critical methodology caveat: the lifts come from BODY-TEXT edits, NOT schema markup; authors explicitly note "less likely to affect search engine rankings"). Vendor claims ("FAQ schema → 2.8× citations," "author schema → 3×") are single-source and unverified by primary research.

Source: Synthesis as of June 2026 — primary literature search.

Confidence: Verified (gap-in-evidence).

Why this matters for Candid: Treat schema as "cheap insurance for eligibility," not a proven AI-visibility lever. The case for schema is defensive (don't be the only competitor without it), not offensive (it won't lift citation by itself).