A subtle but profound difference
Measurement is the process of experimentally obtaining one or more numerical values that can reasonably be attributed to a quantity or property. Measurement is fundamental to almost all human activity and so it is important that the accuracy of any measurement is fit for its intended purpose.
Metrology is the science of measurement and its application. Metrology is not just about the routine making of measurements, it’s about the infrastructure that ensures that we have confidence in the accuracy of the measurement. It establishes a common understanding of units and measurement processes, crucial to human activity.
Metrology covers the accuracy, precision and repeatability of a measurement. It involves traceability or comparison with a “standard” or between different measuring systems. Metrology includes all theoretical and practical aspects of measurement, whatever the measurement uncertainty or the field of application.
Richard Brown, NPL’s Head of Metrology explains: “If philosophy is ‘thinking about thinking’, then metrology is ‘measuring the measurement’.”
Read more about Metrology from the BIPM
So, what is a National Metrology Institute?
Most countries have their own National Metrology Institute which is recognised globally and is part of an international system which facilitate recognition of national measurement standards and measurement capabilities. National metrology institutes (NMIs) have the responsibility of maintaining national measurement standards and disseminating the international System of Units (SI French version of the name) nationally.
NPL is the UK’s National Metrology Institute. In the UK there is a National Measurement System (NMS) which is a network of NPL and other laboratories and processes that provide measurement standards, calibration and testing facilities. The NMS maintains the measurement infrastructure, represents the position of UK measurement internationally and influences the development of documentary standards.
In short, many people do measurement, but few do metrology.
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