Webinar explores future definition of ‘measurement uncertainty’
On 2 July 2025, the BIPM hosted a live webinar to present and discuss a proposed new definition of one of the most fundamental concepts in metrology: measurement uncertainty.
Organized by the Joint Committee for Guides in Metrology (JCGM), the webinar attracted more than 2,000 participants across Zoom, YouTube and LinkedIn—demonstrating the global importance and wide-reaching interest in this foundational topic.
The proposed new definition has been developed by JCGM Working Groups 1 and 2, which are responsible for maintaining the Guide to the Expression of Uncertainty in Measurement (GUM) and the International Vocabulary of Metrology (VIM). This update will be featured in the next committee draft of the fourth edition of the VIM (VIM4).
The current definition in the VIM (3rd edition, 2008) describes measurement uncertainty as: “non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used.”
The proposed new definition is intended to improve clarity and accessibility across disciplines: “doubt about the value of the measurand that remains after making a measurement.”
The high level of engagement—reflected in the volume of questions and comments received during the webinar and via LinkedIn—confirms the relevance of this work to a broad range of stakeholders. These contributions are now being reviewed by the JCGM as part of the ongoing revision process.
Watch a recording of the webinar
Including presentations from members of the JCGM Working Groups and a live Q&A moderated by the BIPM