Treatment of bias in estimating measurement uncertainty

O’Donnell, Gregory E.; Hibbert, David Brynn

doi:10.1039/b414843f

Cited by 46 publications

(20 citation statements)

References 13 publications

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“…Further fuller statistical studies could be performed in 30 s; typically 30 measurements is required for such a study which takes consideration of normality and confidence intervals. There is a suspected bias in the results as most measurements were under-estimates which if shown to systematic, can be corrected for in an evaluation that achieves a large number of repeated measurements [46]. This then opens considerations of experimental design for statistical evaluation of which there is much applicable literature from a metrological perspective.…”

Section: Discussionmentioning

confidence: 99%

Towards in-process x-ray CT for dimensional metrology

Warnett

Titarenko

Kiraci

et al. 2016

Meas. Sci. Technol.

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X-ray computed tomography (CT) offers significant potential as a metrological tool, given the wealth of internal and external data that can be captured, much of which is inaccessible to conventional optical and tactile coordinate measurement machines (CMM). Typical lab-based CT can take upwards of 30 min to produce a 3D model of an object, making it unsuitable for volume production inspection applications. Recently a new generation of real time tomography (RTT) x-ray CT has been developed for airport baggage inspections, utilising novel electronically switched x-ray sources instead of a rotating gantry. This enables bags to be scanned in a few seconds and 3D volume images produced in almost real time for qualitative assessment to identify potential threats. Such systems are able to scan objects as large as 600 mm in diameter at 500 mm s −1 . The current voxel size of such a system is approximately 1 mm-much larger than lab-based CT, but with significantly faster scan times is an attractive prospect to explore. This paper will examine the potential of such systems for real time metrological inspection of additively manufactured parts. The measurement accuracy of the Rapiscan RTT110, an RTT airport baggage scanner, is evaluated by comparison to measurements from a metrologically confirmed CMM and those achieved by conventional lab-CT. It was found to produce an average absolute error of 0.18 mm that may already have some applications in the manufacturing line. While this is expectedly a greater error than labbased CT, a number of adjustments are suggested that could improve resolution, making the technology viable for a broader range of in-line quality inspection applications, including cast and additively manufactured parts.

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Section: Discussionmentioning

confidence: 99%

Towards in-process x-ray CT for dimensional metrology

Warnett

Titarenko

Kiraci

et al. 2016

Meas. Sci. Technol.

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“…Ideally, the CRM used should be of the same matrix. When a CRM is not available then a standard material purchased from a reputable supplier will need to suffice’[26].…”

Section: Methodsmentioning

confidence: 99%

An international quality control programme for PRISM chemiluminescent immunoassays in blood service and blood product laboratories

et al. 2009

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Analysis of test results of an external QC sample can be used as a statistical process control through ongoing measurement of imprecision. When laboratories test the same QC sample in the same assay and submit test results to a single database, the results can be compared and a measure of bias can be calculated. The resulting QC programme can offer detection of unexpected variation in the testing processes and the source of variation investigated.

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“…Quality control procedures aimed at controlling analytical variation based on internal quality control will not capture all sources of variation. Only procedures that include all sources of variation will enable us to get to grips with the real total MU when measuring patient samples [12].…”

Section: Are the Differences Between Te And Mu Reconcilable?mentioning

confidence: 99%

Total error vs. measurement uncertainty: revolution or evolution?

Oosterhuis

Theodorsson

2016

Clinical Chemistry and Laboratory Medicine (CCLM)

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Abstract:The first strategic EFLM conference "Defining analytical performance goals, 15 years after the Stockholm Conference" was held in the autumn of 2014 in Milan. It maintained the Stockholm 1999 hierarchy of performance goals but rearranged them and established five task and finish groups to work on topics related to analytical performance goals including one on the "total error" theory. Jim Westgard recently wrote a comprehensive overview of performance goals and of the total error theory critical of the results and intentions of the Milan 2014 conference. The "total error" theory originated by Jim Westgard and co-workers has a dominating influence on the theory and practice of clinical chemistry but is not accepted in other fields of metrology. The generally accepted uncertainty theory, however, suffers from complex mathematics and conceived impracticability in clinical chemistry. The pros and cons of the total error theory need to be debated, making way for methods that can incorporate all relevant causes of uncertainty when making medical diagnoses and monitoring treatment effects. This development should preferably proceed not as a revolution but as an evolution.

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Treatment of bias in estimating measurement uncertainty

Cited by 46 publications

References 13 publications

Towards in-process x-ray CT for dimensional metrology

Towards in-process x-ray CT for dimensional metrology

An international quality control programme for PRISM chemiluminescent immunoassays in blood service and blood product laboratories

Total error vs. measurement uncertainty: revolution or evolution?

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