{
 "question": "Do Google AI Mode and Google AI Overviews behave as one search surface or two, and at which stage of visibility (appearance, citation, ranking-to-citation, prominence, cross-surface transfer) do they differ?",
 "population": "400 US keywords (50 per industry, 20 highest-volume and 30 random per industry) from the study 4 sample, 32 seed topics; Google organic results with AI Overview and Google AI Mode, Google.com, US, English, desktop, 26 September 2026, one request each. Version 1.1 re-analyzes the same responses; no new queries.",
 "inclusion": "All 400 searches for appearance, citation and transfer; the 236 searches where both surfaces cited at least one source for overlap, prominence and paired comparisons; the 253 searches where both surfaces appeared for ranking-to-citation.",
 "exclusion": "",
 "calculations": [
  "Citations: every cited link in each answer (element references and links in reading order, then top-level references), normalized and de-duplicated.",
  "Jaccard similarity = shared / union per search; overlap coefficient = shared / smaller set; domain overlap excludes google.com unless stated.",
  "First source = first link cited inside the answer body.",
  "Ranking-to-citation = share of organic top-10 URLs that the surface cites, overall and by position band.",
  "Paired differences per search (AI Mode minus AI Overview) for Google-owned share, forum/social/video share, top-10 share and number of sources, with the share of searches in each direction.",
  "Concentration: registrable domains counted once per answer; Herfindahl-Hirschman index and effective number of domains = 1/HHI.",
  "Moderators: OLS of per-search URL Jaccard on industry, intent (DataForSEO keyword intent) and stratum, standard errors clustered by seed topic; joint Wald tests.",
  "Intervals: 95% bootstrap resampling the 32 seed topics (2,000 resamples, seed 20260926)."
 ],
 "limitations": [
  "One run per surface and search on one date: stability across runs, dates and wordings is not measured, so part of the gap may be ordinary run-to-run variation.",
  "Observational: the study shows which sources each surface cites, not why; ranking in the top 10 is the only observable retrieval stage, and a page can be retrieved without ranking there.",
  "Citation is not influence or attribution: whether a cited page supports the sentence it is attached to, and whether it shaped the answer, is not measured; nor are clicks or user outcomes.",
  "AI Mode was queried as a first question, not as a follow-up in a conversation.",
  "Source types use a fixed domain list; intent is DataForSEO's keyword label, not model-coded."
 ],
 "update": "A second collection date is planned with study 24 (week-over-week volatility); the page will add stability figures then.",
 "@context": "https://schema.org",
 "@type": "Dataset",
 "name": "AI Mode vs AI Overviews: how different are the sources?",
 "version": "1.1",
 "dateCreated": "2026-09-26",
 "creator": {
  "@type": "Organization",
  "name": "Underneath",
  "url": "https://underneath.agency"
 },
 "url": "https://underneath.agency/research/ai-mode-vs-ai-overviews-study",
 "temporalCoverage": "2026-09-26",
 "isAccessibleForFree": true,
 "license": "https://creativecommons.org/licenses/by/4.0/",
 "code": "cite/pipeline/ (collection, validation and analysis scripts)",
 "variableMeasured": [
  "reanalyzed",
  "collected",
  "n_searches",
  "n_seed_topics",
  "bootstrap",
  "outcome_states",
  "appearance",
  "transfer_all",
  "n_both_cited",
  "overlap",
  "overlap_sensitivity",
  "prominence",
  "ranking_to_citation",
  "paired",
  "moderators",
  "moderator_model",
  "concentration_both_cited",
  "source_types_both_cited",
  "n_citations_both_cited",
  "median_sources_both_cited",
  "composition"
 ],
 "dateModified": "2026-09-28",
 "research_questions": {
  "RQ1": "Appearance and citation: how often does each surface answer and cite, counting every search?",
  "RQ2": "Source selection: how much do the cited URLs and domains overlap for the same search, and how robust is that to the overlap measure?",
  "RQ3": "Ranking to citation: given that a URL ranks in the organic top 10, how likely is each surface to cite it?",
  "RQ4": "Prominence: do the surfaces lead with the same source?",
  "RQ5": "Moderators: does the gap depend on industry, search intent or sample stratum?",
  "RQ6": "Stability across runs, dates, wordings and conversation turns. Not answered: one run per surface and search."
 },
 "framework": "Visibility is treated as a set of stages, not one score: appearance, citation, ranking-to-citation, prominence, cross-surface transfer. Attribution accuracy, influence on the answer and user outcomes are named but not measured."
}