{"id":2066,"slug":"caveats-correlational-vs-causal-evidence-base","title":"Caveats — only three causal findings; everything else is correlational or vendor-claimed","kind":"reference","scope":"business","status":"current","audiences":["kevin","candid-team"],"topics":["digital-presence-work-tiers"],"reference_body":"**Honest gaps:**\n\n1. **Only three findings rise to genuinely causal:**\n   - **Reviews → revenue** (Luca regression-discontinuity Yelp study — see sister brief [[research-brief-smb-widget-market-difficulty-june-2026]])\n   - **Page speed → conversion** (Google/SOASTA + web.dev A/B partners — [[google-soasta-2017-bounce-probability]])\n   - **GBP mechanics → local-pack presence** (Sterling Sky/Whitespark controlled tests — [[sterling-sky-controlled-tests-debunked-tactics]])\n\n   Local-SEO weightings, content timelines, review thresholds, schema CTR lifts, and tool-linkability figures are correlational, survey-based, or vendor self-reports.\n\n2. **Survivorship and selection bias are pervasive,** especially for content and interactive tools. Treat all agency case studies as a biased sample of winners.\n\n3. **Recency and drift.** AI Overview citation behavior is changing rapidly; CWV pass rates and review-threshold expectations shift annually. Treat any single-year figure as a snapshot and design tiers to be robust to these shifts.\n\n4. **Vertical variation.** Ranking-factor weights and review dynamics vary by industry (proximity matters more for home services; reviews + content relevance more for restaurants and professional services). Treat the tiers as universal but acknowledge that within-tier priorities shift by vertical — see sister brief [[research-brief-smb-widget-vertical-difficulty-june-2026]].","rationale_body":null,"metadata":null,"links":{"outgoing":[],"incoming":[{"slug":"research-brief-smb-widget-difficulty-to-work-june-2026","title":"Research brief: SMB widget difficulty-to-work mapping — three tiers of work for three sizes of gap (June 2026)","kind":"reference","scope":"business","link_type":"relates-to"}]},"created_at":"2026-06-23T19:16:02.768Z","updated_at":"2026-06-23T19:16:02.768Z"}