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    "Pooled standard deviation: s_p = √(Σ ν_i s_i² / Σ ν_i) from k≥2 stated groups. ν_i > 0 and finite.",
    "s_i ≥ 0. Both zero is valid (s_p = 0).",
    "Not Type A from one sample, not Welch–Satterthwaite ν_eff, and not ISO 21748 u of a mean."
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    "Does not compute ISO 21748 u of a mean"
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    "k = 1 → VALUE_OUT_OF_RANGE",
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  "sources": [
    {
      "title": "JCGM 100:2008 — Evaluation of measurement data (GUM)",
      "section": "4.2.4 Type A evaluation from several series",
      "url": "https://www.bipm.org/en/publications/guides/gum.html",
      "supports": "Independent series of observations of the same measurand may be pooled: s_p² is the ν-weighted mean of the sample variances.",
      "kind": "standard"
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    {
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      "section": "Pooled repeatability standard deviation",
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