{
  "example_kind": "original synthetic manual planning case",
  "slug": "forecast-vintage-retention",
  "title": "Preserve the forecast made before the outcome",
  "scenario": "Synthetic planning case: Before a proof starts, a duration forecast of three days is saved. After the actual six-day finish, a recap changes the forecast field to six and reports zero error.",
  "layout": "protocol",
  "dataset": {
    "heading": "Inspect the invented case records",
    "headers": [
      "Record",
      "Timing",
      "Duration value",
      "Evaluation use"
    ],
    "rows": [
      [
        "Original prediction",
        "Before start",
        "3 days",
        "Eligible original forecast"
      ],
      [
        "Observed result",
        "After finish",
        "6 days",
        "Outcome"
      ],
      [
        "Recap replacement",
        "After outcome",
        "6 days",
        "Not a genuine earlier prediction"
      ]
    ]
  },
  "derivation": "Original signed error=6−3=3 days. Using the post-outcome replacement gives 6−6=0 but changes the evidence vintage and invalidates that evaluation.",
  "result": "Evaluate the original three-day forecast against the six-day outcome, giving a three-day signed error. Preserve the after-outcome recap as a different record, not a replacement prediction.",
  "boundary": "The artifact protects prospective evaluation from replacing a saved forecast with hindsight.",
  "limitations": "A timestamp alone does not prove the complete training or information boundary. This worksheet preserves the stated prediction vintage only.",
  "sources": [
    "forecast"
  ],
  "tasks": [
    [
      "Retain original forecast evidence",
      "Recorder",
      "The three-day prediction and its pre-outcome timestamp remain immutable in the evaluation ledger."
    ],
    [
      "Separate recap from prediction",
      "Reviewer",
      "The six-day recap is labelled after-outcome information."
    ],
    [
      "Evaluate the declared vintage",
      "Planning lead",
      "The three-day error is reported for the original forecast rather than a hindsight value."
    ]
  ],
  "faqs": [
    [
      "May forecasts be updated before outcomes?",
      "Yes. Keep each dated vintage and evaluate it at its own declared horizon; do not erase the earlier prediction."
    ],
    [
      "Does a corrected clerical entry require the same treatment?",
      "Record the correction reason and evidence explicitly instead of silently rewriting the evaluated record."
    ]
  ],
  "method_references": [
    {
      "id": "forecast",
      "title": "Forecasting: Principles and Practice — accuracy",
      "url": "https://otexts.com/fpp3/accuracy.html",
      "scope": "Genuine held-out forecast and point-error evaluation context. Binary scoring examples use their own explicit toy definitions; no real task model is validated."
    }
  ]
}