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Uncertain results From November 2010 newsletter

Uncertain results

All measurements are inexact to some degree. Calculating this measurement uncertainty (MU) and, importantly, assessing what it means can appear daunting. However, it is a key factor in evaluating the significance of analytical results and is becoming increasingly important for accreditation purposes. We have produced a short introductory guide to MU. Keith Jewell explains the take–home messages:

"ISO 17025 requires laboratories to accompany a result with an estimate of MU when it is relevant to the validity or application of the test results, when a client's instruction so requires, or when the uncertainty affects compliance with a specification limit. So it is important that you understand the background to how it is estimated and therefore be confident that it contains all relevant uncertainty components. A smaller MU does not necessarily mean a better measurement. It could imply that fewer factors have been taken into account."

To receive a copy of the guide, send an e–mail to with the subject line: send uncertainty

Contact: Keith Jewell
+44(0)1386 842055