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12.5: Quantitative Precision

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    142473

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    13.5 Writing with Quantitative Precision

    Engineering writing has one standard that distinguishes it from other technical writing: every significant claim must be supported by a number with a unit.

    Weak and strong examples of quantitative engineering writing.
    Weak (unverifiable) Strong (verifiable)
    "The results seem high." "Maximum tension is 21,500 N, exceeding the 18,000 N allowable by 19%."
    "The resistor gets hot." "Dissipation is 0.436 W, 74% above the 0.25 W rating."
    "Velocity increases near the middle." "Velocity peaks at 10.5 ft/s at d = 250 ft, 47% higher than the near-tower minimum of 7.2 ft/s."
    "The mass looks right." "Calculated mass is 221.95 g; Fusion shows 221.954 g — agreement to 4 significant figures."
    "Safety factor is adequate." "Actual SF = 2.08, exceeding the required SF = 2.0 by 4%."

    Significant figures: report results to appropriate precision — not more, not fewer. Reporting \(I = 0.03\) A implies one significant figure. \(I = 0.030\) A correctly communicates two. \(I = 0.030909090909\) A implies false precision. Units always: a number without a unit in an engineering document is an error.


    This page titled 12.5: Quantitative Precision was last modified on Thu, 24 Sep 2026 17:38:18 GMT and is shared under a CC BY-NC license and was authored, remixed, and/or curated by .

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