{
  "version": 1,
  "topic": "DC09",
  "title": "Preparing production data before a decline study",
  "createdAt": "2026-10-24",
  "case": {
    "title": "Calendar versus producing-day rate",
    "premise": "A 30-day month contains 15,000 STB of allocated production. Only the number of active days changes.",
    "formula": "calendar rate = volume/30; on-stream rate = volume/active days",
    "variables": "The two rates use different denominators. No production-history cleaning or parameter fitting occurs in this calculation.",
    "steps": [
      {
        "label": "Define the baseline",
        "calculation": "Active days = 15",
        "explanation": "A 30-day month contains 15,000 STB of allocated production. Only the number of active days changes."
      },
      {
        "label": "Select the relation",
        "calculation": "calendar rate = volume/30; on-stream rate = volume/active days",
        "explanation": "The two rates use different denominators. No production-history cleaning or parameter fitting occurs in this calculation."
      },
      {
        "label": "Substitute the values",
        "calculation": "15,000/30 = 500 STB/calendar day; 15,000/15 = 1,000 STB/active day",
        "explanation": "Retain intermediate precision. The displayed values are rounded only after evaluation."
      },
      {
        "label": "Read the result",
        "calculation": "Calendar rate (STB/day) = 500; On-stream rate (STB/active day) = 1000",
        "explanation": "Uptime changes the on-stream interpretation without changing the month's allocated volume."
      }
    ],
    "result": "Calendar rate (STB/day) = 500; On-stream rate (STB/active day) = 1000",
    "interpretation": "Uptime changes the on-stream interpretation without changing the month's allocated volume.",
    "control": "Active days",
    "columns": [
      "Active days",
      "Calendar rate (STB/day)",
      "On-stream rate (STB/active day)"
    ],
    "rows": [
      [
        10,
        500,
        1500
      ],
      [
        15,
        500,
        1000
      ],
      [
        20,
        500,
        750
      ],
      [
        25,
        500,
        600
      ],
      [
        30,
        500,
        500
      ]
    ],
    "baseline": 1,
    "rowNotes": [
      "Active days = 10. Calendar rate (STB/day): 500; On-stream rate (STB/active day): 1500.",
      "Active days = 15. Calendar rate (STB/day): 500; On-stream rate (STB/active day): 1000.",
      "Active days = 20. Calendar rate (STB/day): 500; On-stream rate (STB/active day): 750.",
      "Active days = 25. Calendar rate (STB/day): 500; On-stream rate (STB/active day): 600.",
      "Active days = 30. Calendar rate (STB/day): 500; On-stream rate (STB/active day): 500."
    ],
    "provenance": "Original synthetic teaching calculation. Equations and fixed controls are stated here; these are not field measurements.",
    "questions": [
      {
        "question": "Reproduce the baseline Calendar rate (STB/day) without rounding intermediate values.",
        "answer": "15,000/30 = 500 STB/calendar day; 15,000/15 = 1,000 STB/active day. Calendar rate (STB/day) = 500. Uptime changes the on-stream interpretation without changing the month's allocated volume."
      },
      {
        "question": "Compare the first and last recorded scenarios. Which input changes?",
        "answer": "Active days changes from 10 to 30. Other controls remain as stated in the premise. Calendar rate (STB/day) changes from 500 to 500."
      },
      {
        "question": "What would be needed to apply this example to a different physical system?",
        "answer": "Replace the synthetic controls with compatible documented inputs and check the relation's assumptions. The two rates use different denominators. No production-history cleaning or parameter fitting occurs in this calculation. Uptime changes the on-stream interpretation without changing the month's allocated volume."
      }
    ]
  },
  "recorded": null
}