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Measurement Uncertainty - practical perspective

Working group 8.42


Measurement uncertainty

The result of a measurement is complete only when accompanied by a quantitative statement of its uncertainty. This measurement uncertainty reflects the incomplete knowledge of the measurand and allows to assess the reliability, the comparability or a risk associated with the measurement result. In metrology, the specification of the uncertainty is essential, e.g. to achieve traceability to the underlying SI unit.


The  Opens external link in new window „Guide to the Expression of Uncertainty in Measurement“ (GUM) offers universally applicable rules for evaluating measurement uncertainties , and  is an internationally recognized guide today. Thus, the GUM enables expressions of uncertainty to be consistent and internationally transferable  – which is a basis for trade and the economy.



Practical support

PTB Working Group 8.42 offers practical support in the field of measurement uncertainty. Statistical issues in line with and beyond the GUM are dealt with in consultations with PTB staff and in collaborations, in research activities (see WG 8.42) and through participation in Committees. To support the assessment of uncertainties according to the rules of the GUM, the Working Group offers Advanced TrainingSoftware Applications facilitate the implementation of these evaluations.

In addition, the Working Group supports legal metrology regarding statistical questions (in the Opens external link in new windowPTB-AK "Statistics for metrology and verification“ and in the Opens external link in new windowWorking Group for Metrology and Verification "Test Centers and Sampling Procedures") and develops sampling procedures and plans for the implementation of Section 35 of the new Measures and Verification Ordinance in agreement with the German verification authorities (see Sampling procedures in legal metrology).

Advanced training measures

PTB Working Group 8.42 regularly offers advanced training, seminars and other events in the field of measurement uncertainty. These promote the application of the GUM and its supplements and improve the understanding of methods for evaluating measurement uncertainty as well as their applicability.

PTB-Seminar “Practical aspects of evaluating measurement uncertainty”

  • For personnel of test and calibration laboratories: every 2 years in spring in Berlin, information about these events (programs and presentations of years 201820162014, 2013, 2012, 2011)
  • The seminar 2023 (22.-23. May, PTB, institute Berlin - further information, here).

Training course ”Introduction to evaluating measurement uncertainty according to the rules of the GUM”

  • Externally organized by the German Calibration Service DKD for its members: 22nd Sept. 2022, 29th Jan. 2019, 22nd March 2017, nearly every 2 years in Berlin
  • Opens external link in new windowFor PTB staff: at least twice each year in Berlin and Braunschweig and on inquiry

To improve the quality, efficiency and dissemination of measurement uncertainty training, the  Mathmet activity MU Training developed freely available training material. For example, PTB developed the following video with partners:

The coverage factor k explained –
From standard uncertainty u to expanded uncertainty U
The coverage factor k explained –
From standard uncertainty u to expanded uncertainty U


A number of software applications are available for evaluating uncertainties according to the rules of the GUM. Some of these applications include:

A comprehensive, up-to-date list of software to evaluate uncertainty as well as their characteristics was developed by the consortium of the activity MU Training and is freely available at the website.



  • Opens external link in new windowGUM-documents to evaluate measurements:

    • JCGM 100:2008      Guide to the expression of Uncertainty in Measurement
    • JCGM 104:2009      An introduction to the GUM and related documents
    • JCGM 101:2008      Propagation of distributions using Monte Carlo method - Suppl.1 to the GUM
    • JCGM 102:2011      Extension to any number of output quantities - Suppl. 2 to the GUM
    • JCGM 106:2012      The role of measurement uncertainty in conformity assessment
    • JCGM GUM-6:2020 Developing and using measurement models

  • PTB statement regarding Initiates file downloadsystematic errors in the calculation of uncertainty in measurements (2019)
  • Opens external link in new windowVIM - International Vocabulary of Metrology


  • Publications related to the evaluation of measurement uncertainty of  the Working Group 8.42 "Data Analysis and Measurement Uncertainty"