Alternative statistical approach to evaluating interlaboratory performance.

1985 ◽  
Vol 31 (1) ◽  
pp. 106-108 ◽  
Author(s):  
S S Ehrmeyer ◽  
R H Laessig
Keyword(s):  
Statistical Approach ◽  
State Of The Art ◽  
Total Error ◽  
Measurement Techniques ◽  
Performance Criteria ◽  
Concurrent Use ◽  
Regulatory Standards ◽  
Percentile Rank ◽  
Realistic Assessment ◽  
A New Technique

Abstract We report a new technique for realistic assessment of laboratory performance as measured by proficiency testing. Interlaboratory results accumulated from 129 participants during 18 months provide the baseline data from which we established "state-of-the-art" performance criteria for three ranges of pH, pCO2, and pO2. By concurrent use of two statistical measurement techniques, the cumulative percentile rank and the algebraic and absolute mean error, laboratories can accurately evaluate their performance in terms of acceptable state-of-the-art criteria, total error, or medical usefulness. The approach facilitates assessment of the nature of the errors that have led to inferior performance and identification of probable areas where improvement is possible. If criteria based on regulatory standards or medical usefulness goals are included, the system can provide a basis for licensure or professional quality improvement.

scholarly journals Performance Criteria for Testosterone Measurements Based on Biological Variation in Adult Males: Recommendations from the Partnership for the Accurate Testing of Hormones

2012 ◽  
Vol 58 (12) ◽  
pp. 1703-1710 ◽  
Author(s):  
Yeo-Min Yun ◽  
Julianne Cook Botelho ◽  
Donald W Chandler ◽  
Alex Katayev ◽  
William L Roberts ◽  
...  
Keyword(s):  
Total Error ◽  
Full Range ◽  
Biological Variation ◽  
Analytical Performance ◽  
Performance Criteria ◽  
Performance Goals ◽  
Adult Males ◽  
Large Variability ◽  
Wide Range ◽  
Variation Data

BACKGROUND Testosterone measurements that are accurate, reliable, and comparable across methodologies are crucial to improving public health. Current US Food and Drug Administration–cleared testosterone assays have important limitations. We sought to develop assay performance requirements on the basis of biological variation that allow physiologic changes to be distinguished from assay analytical errors. METHODS From literature review, the technical advisory subcommittee of the Partnership for the Accurate Testing of Hormones compiled a database of articles regarding analytical and biological variability of testosterone. These data, mostly from direct immunoassay-based methodologies, were used to specify analytical performance goals derived from within- and between-person variability of testosterone. RESULTS The allowable limits of desirable imprecision and bias on the basis of currently available biological variation data were 5.3% and 6.4%, respectively. The total error goal was 16.7%. From recent College of American Pathologists proficiency survey data, most currently available testosterone assays missed these analytical performance goals by wide margins. Data from the recently established CDC Hormone Standardization program showed that although the overall mean bias of selected certified assays was within 6.4%, individual sample measurements could show large variability in terms of precision, bias, and total error. CONCLUSIONS Because accurate measurement of testosterone across a wide range of concentrations [approximately 2–2000 ng/dL (0.069–69.4 nmol/L)] is important, we recommend using available data on biological variation to calculate performance criteria across the full range of expected values. Additional studies should be conducted to obtain biological variation data on testosterone from women and children, and revisions should be made to the analytical goals for these patient populations.

Automated Anthropometric Measuring Devices for Use in Mass-Screening

2000 ◽  
Vol 44 (38) ◽  
pp. 719-722
Author(s):  
William F. Moroney
Keyword(s):  
Mass Screening ◽  
State Of The Art ◽  
Measurement Techniques ◽  
The State ◽  
Anthropometric Measurement ◽  
Review Of The Literature ◽  
Measuring Devices ◽  
Measurement Devices ◽  
Electro Magnetic

The purpose of this paper is to describe the state of the art in anthropometric measuring devices used for mass screening. In addition, technologies which could be used for automated mass screening are identified and described. A review of the literature identified only two operational anthropometric measurement devices currently used for mass screening. A variety of potentially applicable measurement techniques including acoustic, light, electro-magnetic, potentiometric/electro-optical (including digitizing arms) technologies were identified and described. Data describing the capabilities and limitations of these systems are also provided.

scholarly journals Overview: Tropospheric profiling: state of the art and future challenges – introduction to the AMT special issue

2014 ◽  
Vol 7 (9) ◽  
pp. 2981-2986 ◽  
Author(s):  
D. Cimini ◽  
V. Rizi ◽  
P. Di Girolamo ◽  
F. S. Marzano ◽  
A. Macke ◽  
...  
Keyword(s):  
International Symposium ◽  
Technology Development ◽  
State Of The Art ◽  
Measurement Techniques ◽  
Special Issue ◽  
Recent Advances ◽  
Future Challenges ◽  
Atmospheric Measurement

Abstract. This paper introduces the Atmospheric Measurement Techniques special issue on tropospheric profiling, which was conceived to host full papers presenting the results shown at the 9th International Symposium on Tropospheric Profiling (ISTP9). ISTP9 was held in L'Aquila (Italy) from 3 to 7 September 2012, bringing together 150 scientists representing of 28 countries and 3 continents. The tropospheric profiling special issue collects the highlights of ISTP9, reporting recent advances and future challenges in research and technology development.

scholarly journals On Residual Stress Development, Prevention, and Compensation in Metal Additive Manufacturing

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 255 ◽  
Author(s):  
Kevin Carpenter ◽  
Ali Tabei
Keyword(s):  
Additive Manufacturing ◽  
Process Parameters ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Measurement Techniques ◽  
Complex Geometries ◽  
Quality Inspection ◽  
Metal Additive Manufacturing ◽  
Computational Costs ◽  
Metal Additive

One of the most appealing qualities of additive manufacturing (AM) is the ability to produce complex geometries faster than most traditional methods. The trade-off for this advantage is that AM parts are extremely vulnerable to residual stresses (RSs), which may lead to geometrical distortions and quality inspection failures. Additionally, tensile RSs negatively impact the fatigue life and other mechanical performance characteristics of the parts in service. Therefore, in order for AM to cross the borders of prototyping toward a viable manufacturing process, the major challenge of RS development must be addressed. Different AM technologies contain many unique features and parameters, which influence the temperature gradients in the part and lead to development of RSs. The stresses formed in AM parts are typically observed to be compressive in the center of the part and tensile on the top layers. To mitigate these stresses, process parameters must be optimized, which requires exhaustive and costly experimentations. Alternative to experiments, holistic computational frameworks which can capture much of the physics while balancing computational costs are introduced for rapid and inexpensive investigation into development and prevention of RSs in AM. In this review, the focus is on metal additive manufacturing, referred to simply as “AM”, and, after a brief introduction to various AM technologies and thermoelastic mechanics, prior works on sources of RSs in AM are discussed. Furthermore, the state-of-the-art knowledge on RS measurement techniques, the influence of AM process parameters, current modeling approaches, and distortion prevention approaches are reported.

scholarly journals A review of the measurement of sediment yield in different scales

2005 ◽  
Vol 58 (3) ◽  
pp. 257-265 ◽  
Author(s):  
José Carlos de Araújo ◽  
Donald W. Knight
Keyword(s):  
Spatial Resolution ◽  
Measurement Technique ◽  
Sediment Yield ◽  
Catchment Area ◽  
Review Paper ◽  
Graphical Representation ◽  
State Of The Art ◽  
Measurement Techniques ◽  
Annual Average ◽  
Global Data

The present review paper has the objective of presenting and briefly discussing the state-of-the-art papers on sediment yield (SY) measurement. About 80 publications are referred to, representing all continents, and more than 30 countries. It is observed that SY measurement technique is a much stronger function of temporal than of spatial resolution. Annual average SY data of 364 catchments are summarized. Global data presents no trend concerning catchment area and the same behavior is observed for the continents, except for Africa, which presents a consistent decrease of SY with increasing area. A graphical representation of the spatial and temporal applicability of the different SY measurement techniques is shown.

Precision requirements for cost-effective operation of analytical processes

1990 ◽  
Vol 36 (9) ◽  
pp. 1629-1632 ◽  
Author(s):  
J O Westgard ◽  
R W Burnett
Keyword(s):  
Total Error ◽  
Cost Effective ◽  
Performance Criteria ◽  
Statistical Quality Control ◽  
Power Functions ◽  
Reliable Detection ◽  
Minimum Requirements ◽  
Control Procedures ◽  
Common Criterion ◽  
Power Curves

Abstract Current performance criteria for analytical methods are often based on recommendations developed many years ago. A common criterion for imprecision requires that two times the standard deviation (s) of the method be less than the allowable total error (TEa). Unfortunately, when this criterion is minimally satisfied, commonly used control procedures cannot achieve reliable detection of medically important errors. Studies of the power functions for statistical quality-control (QC) procedures show that the magnitude of medically important errors must be at least 3s to fall near the plateau of the power curves and be readily detected by current QC procedures. For methods that just meet the precision criterion 2s less than TEa, however, medically important errors will fall on the rising portion of the power curves and typically be detected less than half of the time. From a "reverse engineering" perspective, the 2s less than TEa criterion is inadequate because it does not allow for the known performance limitations (lack of sensitivity) of commonly used control procedures. A strong case can be made for using a criterion of at least '4s less than TEa, which calls for a twofold improvement in imprecision over, the current minimum requirements. This recommendation is consistent with current industrial guidelines for process capability and would lead to more reliable detection of medically important errors.

Residual stress measurement techniques for Ti6Al4V parts fabricated using selective laser melting: state of the art review

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ruben B.O. Acevedo ◽  
Klaudia Kantarowska ◽  
Edson Costa Santos ◽  
Marcio C. Fredel
Keyword(s):  
Residual Stress ◽  
Selective Laser Melting ◽  
Stress Measurement ◽  
State Of The Art ◽  
Measurement Techniques ◽  
Residual Stress Measurement ◽  
Hole Drilling ◽  
X Ray Diffraction ◽  
Laser Melting ◽  
Content Type

Purpose This paper aims to generate a review of available techniques to measure Residual Stress (RS) in Ti6Al4V components made by Ti6Al4V. Design/methodology/approach State of the art; literature review in the field of Residual Stress measurement of Ti6Al4V parts made by selective laser melting (SLM). Findings Different Residual Stress measurement techniques were detailed, regarding its concept, advantages and limitations. Regarding all researched references, hole drilling (semi destructive) and X-ray diffraction (nondestructive) were the most cited techniques for Residual Stress measurement of Ti6Al4V parts made by SLM. Originality/value An extensive analysis of RS measurement techniques for Ti6Al4V parts made by SLM.

scholarly journals Self-Supervised Learning for Generalizable Out-of-Distribution Detection

2020 ◽  
Vol 34 (04) ◽  
pp. 5216-5223 ◽  
Author(s):  
Sina Mohseni ◽  
Mandar Pitale ◽  
JBS Yadawa ◽  
Zhangyang Wang
Keyword(s):  
Neural Networks ◽  
Autonomous Vehicles ◽  
Deep Neural Networks ◽  
State Of The Art ◽  
Feature Learning ◽  
Detection Methods ◽  
Training Set ◽  
Safety Critical ◽  
Multiple Image ◽  
A New Technique

The real-world deployment of Deep Neural Networks (DNNs) in safety-critical applications such as autonomous vehicles needs to address a variety of DNNs' vulnerabilities, one of which being detecting and rejecting out-of-distribution outliers that might result in unpredictable fatal errors. We propose a new technique relying on self-supervision for generalizable out-of-distribution (OOD) feature learning and rejecting those samples at the inference time. Our technique does not need to pre-know the distribution of targeted OOD samples and incur no extra overheads compared to other methods. We perform multiple image classification experiments and observe our technique to perform favorably against state-of-the-art OOD detection methods. Interestingly, we witness that our method also reduces in-distribution classification risk via rejecting samples near the boundaries of the training set distribution.

Using the hazard ratio to evaluate allowable total error in predictive measurands

2016 ◽  
Vol 0 (0) ◽  
Author(s):  
Arne Åsberg ◽  
Ingrid Hov Odsæter ◽  
Gustav Mikkelsen ◽  
Gunhild Garmo Hov
Keyword(s):  
Measurement Errors ◽  
Cox Regression ◽  
State Of The Art ◽  
Total Error ◽  
Biological Variation ◽  
Hazard Ratio ◽  
Published Data ◽  
Acceptable Error ◽  
Albumin Creatinine Ratio ◽  
Urine Albumin

AbstractAllowable total error is usually derived from data on biological variation or from state-of-the-art of measuring technology. Here we present a new principle for evaluating allowable total error when the concentration of the analyte (the measurand) is used for prediction: What are the predictive consequences of allowable total errors in terms of errors in the estimate of the hazard ratio (HR)?We explored the effect of analytical measurement errors on Cox regression estimates of HR. Published data on Cox regression coefficients were used to illustrate the effect of measurement errors on predicting cardiovascular events or death based on serum concentration of cholesterol and on progression of chronic kidney disease to kidney failure based on serum concentrations of albumin, bicarbonate, calcium and phosphate, and urine albumin/creatinine-ratio.If the acceptable error in the estimate of the HR is 10%, allowable total errors in serum cholesterol, bicarbonate and phosphate are approximately the same as allowable total error based on biological variation, while allowable total error in serum albumin and calcium are a little larger than estimates based on biological variation.Evaluating allowable total error from its effect on the estimate of HR is universally applicable to measurands used for prediction.

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