Introduction to the ISO Guide to the Expression of Uncertainty of Measurement (GUM)
When an instrument is calibrated, the measurements should be traceable back to a common standard such as the international system of units (SI). By definition, one cannot have a traceable measurement without uncertainty, which means we have to estimate it and communicate it in each step of the traceability chain. If traceability is important to you, then you must be able to understand and quantify uncertainty.
Estimating measurement uncertainty is one of the most challenging tasks that metrologists and calibration technicians face. The ISO Guide to the Expression of Uncertainty in Measurement (GUM) was produced in 1993 by the Comite international des Poids et Mesures (CIPM) and the International Bureau of Weights and Measures (BIPM) as ISO/IEC Guide 98.
The GUM was developed to
- Provide rules on the expression of measurement uncertainty
- Promote full information on how the uncertainty statements are arrived at
- Provide a basis for the international comparison of measurement results
All calibration laboratories around the world use the GUM method to estimate measurement uncertainty. You can download it here: http://www.bipm.org/en/publications/guides/
Here is an overview of the GUM 8-step process for calculating uncertainty:
- Describe the measured value in terms of your measurement process.
- List the input quantities.
- Determine the uncertainty for each input quantity.
- Evaluate any covariances/correlations in input quantities.
- Calculate the measured value to report.
- Correctly combine the uncertainty components.
- Multiply the combined uncertainty by a coverage factor.
- Report the result in the proper format.
If you would like more information on this topic, I am presenting a web seminar:
ISO Guide to the Expression of Uncertainty in Measurement (GUM) Introduction
Wednesday, January 20, 2016
8:00 am Pacific Standard Time
Duration: 1 hour
What you will learn in this web seminar
Estimating measurement uncertainty is one of the most challenging tasks that metrologists and calibration technicians face. This web seminar introduces you to the ISO Guide to the Expression of Uncertainty in Measurement (GUM). This document was produced in 1993 in order to have a standard way to compute and communicate measurement uncertainty. All calibration laboratories around the world use the GUM method to estimate measurement uncertainty. We’ll provide information on the history of the GUM’s development and the fundamental concepts of the GUM. This web seminar is intended for calibration technicians, new metrologists or metrology engineers. The information presented provides a foundation for other Fluke Calibration web seminars that present measurement uncertainty analyses for specific calibration applications.
Share this with your colleagues:
- New Products
- Electrical Calibration
- RF Calibration
- Data Acquisition and Test Equipment
- Temperature Calibration
- ITS-90 Temperature Standards
- Calibration Baths
- Industrial Calibrators
- Digital Thermometer Readouts
- Multifunction Calibrators
- Temperature Calibration Software
- Pressure Calibration
- Piston Gauges
- Automated Pressure Controller/Calibrators
- Pressure Monitors
- Deadweight Testers
- Manual Pressure Calibration
- Air Data Calibration
- Environmental Monitors
- Pressure Calibration Accessories
- Pressure Calibration Custom Systems
- Pressure Calibration Software
- Flow Calibration
- Process Calibration Tools
- Temperature Calibrators
- Pressure Calibrators
- Multifunction Calibrators
- mA Loop Calibrators
- Process Calibration Software
- Calibration Software
- Humidity Calibration
- Handheld Test Tools
- Purchase Info
- Training and Events
- Literature and Education
- Service and Support
- Service Request (RMA)
- Calibration and Repair Services
- Authorized Service Centers
- Service Plans
- My MET/SUPPORT
- Calibration Community Site
- Register Products
- Product Manuals (User Guides)
- Software Downloads
- Safety, Service, and Product Notices
- Technical Support
- Safety Data Sheets (SDS)
- About Us