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 firstname.lastname@example.org with the subject line: send uncertainty
Contact: Keith Jewell