Ramsey_et_al-2017-Accreditation_and_Quality_Assurance.pdf (715.91 kB)
Combined uncertainty factor for sampling and analysis
journal contribution
posted on 2023-06-09, 06:25 authored by Michael H Ramsey, Stephen L R EllisonMeasurement uncertainty that arises from primary sampling can be expressed as an uncertainty factor, which recognises its sometimes approximately log-normal probability distribution. By contrast, uncertainty arising from chemical analysis is usually expressed as relative uncertainty, based upon the assumptions of its approximately normal distribution. A new method is proposed that enables uncertainty from these two sources, expressed in these different ways, to be combined to produce an estimate of the total combined uncertainty of the measurement values that result when the measurement process is considered as a whole.
History
Publication status
- Published
File Version
- Published version
Journal
Accreditation and Quality AssuranceISSN
0949-1775Publisher
Springer VerlagExternal DOI
Issue
4Volume
22Page range
187-189Department affiliated with
- Evolution, Behaviour and Environment Publications
Notes
In the penultimate paragraph of the original publication, a confidence interval of 93 mg/kg to 971 mg/kg was reported. These values should be 114.5 mg/kg to 786.2 mg/kg. The intended exponent in the calculation was given as a multiplicative factor. The correct calculation is 300/1.619² to 300 × 1.619², since the expanded uncertainty factor is UF = (u')? , in this case giving UF = (u')² Official URL: https://doi.org/10.1007/s00769-017-1305-5 - linked in 'Related URLs' belowFull text available
- Yes
Peer reviewed?
- Yes