{
  "slug": "search-market-share-change",
  "name": "Search market share change",
  "aliases": [
    "Share delta",
    "Period-over-period share move"
  ],
  "definition": "The period-over-period move in your CTR-modeled search market share, returned as an absolute difference in share points alongside a proportional change.",
  "category": "Search market share",
  "type": "derived metric",
  "unit": "share points for the absolute move",
  "direction": "higher-better",
  "verification": "review",
  "aggregation": "Not summable. Each period pair produces its own difference; chaining them does not give a longer-period move.",
  "grain": "One segment × period pair × medium.",
  "dimensions": [
    "intent",
    "brand",
    "keyword",
    "page",
    "category",
    "country",
    "rank_bucket"
  ],
  "requiredFilters": [
    "segment_id",
    "selected_period",
    "comparison_range",
    "source_medium"
  ],
  "sources": [
    "rank-tracking"
  ],
  "reports": [
    "search-market-share-report"
  ],
  "skills": [
    "market-share-review",
    "weekly-search-report",
    "monthly-exec-review",
    "significance-referee"
  ],
  "verbs": [
    "growth_vs_market_share",
    "market_share_breakdown",
    "competitive_trends"
  ],
  "rungs": [
    "R2"
  ],
  "levers": [
    "L2"
  ],
  "questions": [
    "Did our search market share move against last month?",
    "Which rows moved most between the two periods?"
  ],
  "caveats": [
    "The comparison leg is the identical query with only the period filter swapped, so any filter difference between the two legs invalidates the pair.",
    "The proportional change is computed as the difference over the earlier value and is returned as a fraction here, while the significance verbs express the same idea as a percent, the two must not be quoted interchangeably.",
    "The share leg's delta is returned unrounded while the count legs beside it are rounded to two decimal places, so a share move and a click move in the same row are not reported at the same precision.",
    "A move is not a verdict: nothing in this figure tests whether the change is distinguishable from noise."
  ],
  "freshness": "~1 day behind, Daily observation, available the following day.",
  "failureModes": [
    "Rendering the fraction as if it were already a percentage, inflating the move a hundredfold.",
    "Calling a share move real without running the significance check."
  ],
  "notSameAs": [
    {
      "slug": "gap-to-leader",
      "why": "The gap compares two domains in one period; this compares one domain across two periods."
    }
  ],
  "related": [
    "search-market-share",
    "gap-to-leader",
    "market-share-table-clicks"
  ],
  "workflows": [],
  "lastVerified": "2026-08-04"
}