The NIST Reference on Constants, Units and Uncertainty Information at the foundation of modern science and technology from the Physical Measurement Laboratory of NIST

Uncertainty of Measurement Results
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Essentials of expressing measurement uncertainty
    Basic definitions
    Evaluating uncertainty components
    Combining uncertainty components
    Expanded uncertainty and coverage factor
    Examples of uncertainty statements

Evaluation of measurement uncertainty
NIST Uncertainty Machine - An online calculator to perform uncertainty evaluations according to the Guide to the Expression of Uncertainty Measurement (GUM), the GUM Supplement 1, and the NIST Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results.

International and U.S. perspectives on measurement uncertainty

Online publications and purchasing information


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Online: February 1998   -   Last update: December 2017