{
  "slug": "tt008.revisions.magnitude",
  "name": "Size of Census restatements, containerised weight",
  "unit": "share",
  "horizon": "long",
  "grade": "observed",
  "grade_means": "Own-recorded live from terrestrial AIS (aisstream.io receiver network); the recording, timestamps and event derivation are ours.",
  "description": "Median absolute proportional change when a containerised-weight figure is restated. Answers how big a typical restatement is, not merely how often one happens. A source that revises often but trivially is different from one that revises rarely but by a third.",
  "instrument": {
    "id": "TT-008",
    "name": "Port ledger",
    "clock": "medium",
    "role": "witness",
    "source": "US Census Bureau, intltrade/imports/porths",
    "source_url": "https://api.census.gov/data/timeseries/intltrade/imports/porths"
  },
  "coverage": {
    "from": "2026-07-30",
    "to": null
  },
  "publishable_ranges": [],
  "status": "suspended",
  "withdrawn": {
    "since": "1970-01-01",
    "until": null,
    "reason": "NO OBSERVATIONS YET. The archive holds 20,618 entries and every one is a `backfill` — our own air_weight_kg column arriving for the first time — with zero genuine restatements. A revision can only be observed by re-fetching a month we already hold and finding it changed, and until 2026-07-30 nothing did that: the weekly timer ran a superseded collector that crashed against the migrated schema. It now re-syncs the last six months every Friday. Lift when the archive holds genuine `revision` or `withdrawn` entries across at least a few distinct months — not on the first one, which could be a one-off.",
    "finding": null
  },
  "citation": "Trimtabist TT-008 Port ledger revision archive. Every figure is compared against what we previously held; the prior value is preserved before any update. Method: portledger/METHOD.md. Grade: observed — this measures OUR OWN record of the source changing, not a figure the source published.",
  "citationShort": "Trimtab TT-008 Port ledger, \"Size of Census restatements, containerised weight\" (retrieved 2026-08-06).",
  "licence": "CC BY 4.0",
  "retrieved_at": "2026-08-06T11:23:06.696Z",
  "urls": {
    "page": "https://trimtabist.com/series/tt008.revisions.magnitude",
    "csv": "https://trimtabist.com/series/tt008.revisions.magnitude.csv",
    "metadata": "https://trimtabist.com/series/tt008.revisions.magnitude.metadata.json"
  }
}