{
  "schemaVersion": "vultax-public-research-data-v1",
  "articleUrl": "https://vultax.com/research/midterm-scorecard-2026",
  "datasets": [
    {
      "title": "The scoring rule, declared now",
      "columns": [
        {
          "name": "Rule",
          "unit": null
        },
        {
          "name": "Declared value",
          "unit": null
        }
      ],
      "rows": [
        [
          "Primary metric",
          "Brier score per contract, (p − o)²"
        ],
        [
          "Price field",
          "Midpoint of best bid and best ask, Yes token order book, checkpoint capture"
        ],
        [
          "Missing price",
          "No bid or no ask: row kept, counted as missing, not scored"
        ],
        [
          "Wide quote",
          "Spread over 10¢: scored and flagged; Tier A shown with and without"
        ],
        [
          "Aggregation",
          "Contract mean and race mean (equal weight per race); multi-outcome Brier as a secondary table"
        ],
        [
          "Placeholders",
          "Lettered stand-in outcomes scored in all-contracts tables, excluded from Tier A means"
        ],
        [
          "Baselines",
          "Constant 50¢ (Brier 0.25) and the 27 October price, same contracts"
        ],
        [
          "Uncertainty",
          "Cluster bootstrap over races, 2,000 resamples, seed 20261103, 90% interval"
        ],
        [
          "Secondary metric",
          "Log loss with prices clipped to 1¢ and 99¢"
        ],
        [
          "Not done",
          "No normalisation of multi-outcome prices in the primary analysis; no poll or venue comparison; no fees, profit or strategy"
        ]
      ],
      "measurementContext": "From rules-v1.json, frozen 17 October 2026. A change after publication appears only as a dated correction on this page.",
      "sources": [
        {
          "label": "Polymarket Gamma API, events under the midterms tag",
          "url": "https://gamma-api.polymarket.com/events?tag_slug=midterms&closed=false&limit=100",
          "note": "The public catalogue swept for the manifest, open and closed events, with offset and keyset paging."
        },
        {
          "label": "Polymarket API documentation",
          "url": "https://docs.polymarket.com/",
          "note": "Order books, midpoints and the public rate limits the captures stay inside."
        },
        {
          "label": "Frozen manifest, rules, code and file hashes",
          "url": "https://vultax.com/datasets/midterm-scorecard-2026/manifest.json",
          "note": "SHA-256 for every published file; the manifest's own hash is inside manifest-v1.json."
        },
        {
          "label": "State election offices",
          "url": "https://www.nass.org/can-I-vote",
          "note": "Where official results are read for the first outcome record."
        }
      ],
      "measurement": {
        "kind": null,
        "temporalCoverage": null,
        "population": null,
        "methodology": null
      },
      "id": "scoring-rule-table",
      "kind": "published-table",
      "description": "Every Polymarket contract about the 2026 US midterms, frozen on 17 October: 13,186 contracts in 1,352 events, a hashed manifest, two price checkpoints and a Brier rule declared before the vote. In 402 of 507 races the favourite already trades at 90¢ or more.",
      "articleUrl": "https://vultax.com/research/midterm-scorecard-2026",
      "sectionUrl": "https://vultax.com/research/midterm-scorecard-2026#scoring-rule",
      "publishedAt": "2026-10-17",
      "modifiedAt": "2026-10-17",
      "version": "9dc8b08bb6a0c1c0e3d89a911e5195ef0cd745e85bf6369386756b686fa94a44",
      "isLive": false,
      "limitations": "Published research snapshots and calculations; these exports do not contain current quotes or live account data. Observation windows and populations are stated in the source captions and methodology. Missing metadata is unknown, not zero. A pre-registered research protocol with a frozen universe and clocks; no scores exist before the election. Prices are Polymarket order-book readings at stated times, not advice.",
      "downloads": {
        "json": "https://vultax.com/research/midterm-scorecard-2026/data.json?dataset=scoring-rule-table",
        "csv": "https://vultax.com/research/midterm-scorecard-2026/data.csv?dataset=scoring-rule-table"
      }
    }
  ]
}