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      "tests"
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  "assumptions": [
    "ISO 5725 duplicate-difference repeatability: s_r = √(Σ d_i² / (2m)) from m≥2 pairs. m=1 is rejected.",
    "d_i may be negative or zero. Both zero is valid (s_r = 0).",
    "Not Type A from a sample of observations, not r = 2.8·s, and not AIAG GRR EV = R̄/d2."
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  "limitations": [
    "Takes duplicate differences — not a sample of observations",
    "m=1 is rejected so this cannot wrap |d|/√2",
    "Does not report r = 2.8·s_r",
    "Not AIAG GRR EV = R̄/d2"
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  "boundary_conditions": [
    "missing d (and no y1+y2) → MISSING_REQUIRED_INPUT",
    "m = 1 → VALUE_OUT_OF_RANGE",
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    "d = [0,0] is valid"
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    {
      "title": "ISO 5725-2 — Repeatability and reproducibility of standard measurement methods",
      "section": "Repeatability variance from duplicate differences",
      "supports": "Each pair contributes d_i²/2 to the within-laboratory variance. Pooled over m pairs, s_r² = Σ d_i² / (2m).",
      "kind": "standard"
    },
    {
      "title": "ISO 5725-1 — Accuracy (trueness and precision) of measurement methods and results",
      "section": "Repeatability standard deviation s_r",
      "supports": "This page estimates s_r from already-formed differences. It does not report the conventional limit r = 2.8·s_r.",
      "kind": "standard"
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      },
      "expect": {
        "s_r": 5,
        "m": 2
      },
      "expectWarning": null,
      "actual": {
        "s_r": 5,
        "m": 2,
        "d": [
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          8
        ]
      },
      "tol": 1e-12
    },
    {
      "id": "boundary-dup-pairs",
      "ok": true,
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      "inputs": {
        "y1": [
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          20
        ],
        "y2": [
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      "expect": {
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      "expectWarning": null,
      "actual": {
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        "m": 2,
        "d": [
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      "tol": 1e-12
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      "inputs": {
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      "expectWarning": null,
      "actual": {
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        "m": 2,
        "d": [
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        ]
      },
      "tol": 1e-12
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      "expectError": "VALUE_OUT_OF_RANGE",
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      "error": "need at least two duplicate pairs"
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      "kind": "property",
      "detail": "5",
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      "golden": 0,
      "boundary": 5,
      "property": 3
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