scholarly journals How Replicates Can Inform Potential Users of a Measurement Procedure about Measurement Error: Basic Concepts and Methods

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 162
Author(s):  
Werner Vach ◽  
Oke Gerke
Keyword(s):  
Measurement Error ◽  
Measurement Procedure ◽  
Statistical Methodology ◽  
Single Measurement ◽  
Conceptual Approach ◽  
Simple Manner ◽  
Scientific Investigations ◽  
Standard Procedures ◽  
Standardized Terminology ◽  
General Statistical

Measurement procedures are not error-free. Potential users of a measurement procedure need to know the expected magnitude of the measurement error in order to justify its use, in particular in health care settings. Gold standard procedures providing exact measurements for comparisons are often lacking. Consequently, scientific investigations of the measurement error are often based on using replicates. However, a standardized terminology (and partially also methodology) for such investigations is lacking. In this paper, we explain the basic conceptual approach of such investigations with minimal reference to existing terminology and describe the link to the existing general statistical methodology. This way, some of the key measures used in such investigations can be explained in a simple manner and some light can be shed on existing terminology. We encourage clearly conceptually distinguishing between investigations of the measurement error of a single measurement procedure and the comparison between different measurement procedures or observers. We also identify an unused potential for more advanced statistical analyses in scientific investigations of the measurement error.

Putting relative complexity estimates to work: a simple and general statistical methodology

2003 ◽  
Vol 319 ◽  
pp. 591-600 ◽  
Author(s):  
Lluis nindexLligonaLligoña Trulla ◽  
Joseph P. Zbilut ◽  
Alessandro Giuliani
Keyword(s):  
Statistical Methodology ◽  
Relative Complexity ◽  
General Statistical

scholarly journals Rarefaction, alpha diversity, and statistics

2017 ◽  
Author(s):  
Amy Willis
Keyword(s):  
Measurement Error ◽  
Microbial Diversity ◽  
Microbial Ecology ◽  
Ecosystem Function ◽  
Unknown Parameter ◽  
Alpha Diversity ◽  
Fundamental Question ◽  
Error Modeling ◽  
Extensive Literature ◽  
Statistical Methodology

AbstractUnderstanding the drivers of microbial diversity is a fundamental question in microbial ecology. Extensive literature discusses different methods for describing microbial diversity and documenting its effects on ecosystem function. However, it is widely believed that diversity depends on the number of reads that are sequenced. I discuss a statistical perspective on diversity, framing the diversity of an environment as an unknown parameter, and discussing the bias and variance of plug-in and rarefied estimates. I argue that by failing to account for both bias and variance, we invalidate analysis of alpha diversity. I describe the state of the statistical literature for addressing these problems, and suggest that measurement error modeling can address issues with variance, but bias corrections need to be utilized as well. I encourage microbial ecologists to avoid motivating their investigations with alpha diversity analyses that do not use valid statistical methodology.

scholarly journals Calibration of a finite element model of Prescale film for wheel-rail normal contact area measurements

Meccanica ◽  
2021 ◽  
Author(s):  
Jagoba Lekue ◽  
Florian Dörner ◽  
Christian Schindler
Keyword(s):  
Finite Element ◽  
Measurement Error ◽  
Contact Area ◽  
Direct Determination ◽  
Element Model ◽  
Measurement Procedure ◽  
Normal Contact ◽  
Research Activities ◽  
Fundamental Requirement

AbstractThis article presents the latest of a series of research activities aimed to determine the deviation originated when Prescale pressure measurement film is used to measure the size and shape of the wheel-rail contact area. Despite being an attractive solution due to the simplicity of the measurement procedure, it is well known that the contact interaction is altered by the presence of the film. Consequently, characterizing and filtering out the systematic measurement error is a fundamental requirement for accurate quantitative assessments. Nevertheless, the complexity of the wheel-rail contact problem, which lacks an analytical solution, hinders the direct determination of correction values. The approach presented here builds on error corrections for simpler Hertzian geometries to calibrate a film model for further use in the wheel-rail contact scenario. The results highlight the marked dependency of the measurement error on wheel and rail roughness and underline the importance of including the film into finite element models that are validated by comparison with experimental observations.

scholarly journals Monitoring of Grouting Compactness in Tendon Duct Using Multi-Sensing Electro-Mechanical Impedance Method

2020 ◽  
Vol 10 (6) ◽  
pp. 2018 ◽  
Author(s):  
Bin Guo ◽  
Dongdong Chen ◽  
Linsheng Huo ◽  
Gangbing Song
Keyword(s):  
Lead Zirconate Titanate ◽  
Prestressed Concrete ◽  
Processing Time ◽  
Structural Integrity ◽  
Physical Property ◽  
Mechanical Impedance ◽  
Lead Zirconate ◽  
Measurement Procedure ◽  
Impedance Method ◽  
Single Measurement

The structural integrity of post-tensioning prestressed concrete structures with tendon ducts highly depends on the grouting quality in construction. This paper proposes a real-time approach to monitoring the grouting compactness in tendon ducts using the multi-sensing electro-mechanical impedance (EMI) method. When Lead Zirconate Titanate (PZT) transducers with different pre-selected dimensions are serially connected and mounted on a structure at distributed locations, each PZT provides unique resonance frequency coupled with the local structural physical property. Therefore, the impedance with multiple peaks of the serially connected multiple PZTs can be captured during a single measurement, which significantly simplifies the measurement procedure and reduces the data processing time. In addition, the wiring for the PZT sensors is also simplified. In this research, the feasibility of the proposed method was experimentally and numerically investigated to monitor the grouting compactness in a tendon duct specimen. The 3-dB mean absolute percentage deviation (MAPD) was applied to quantify the variations of the impedance signatures measured from five different grouting levels. Both experimental and numerical results verify the feasibility of using the proposed method for monitoring the grouting compactness in tendon ducts.

scholarly journals A Primer on Network Meta-Analysis for Dental Research

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Yu-Kang Tu ◽  
Clovis Mariano Faggion
Keyword(s):  
Statistical Approach ◽  
Meta Analysis ◽  
Statistical Methodology ◽  
Close Collaboration ◽  
Dental Research ◽  
Modelling Framework ◽  
Statistical Framework ◽  
General Statistical ◽  
Multiple Treatments ◽  
Further Development

In the last decade, a new statistical methodology, namely, network meta-analysis, has been developed to address limitations in traditional pairwise meta-analysis. Network meta-analysis incorporates all available evidence into a general statistical framework for comparisons of all available treatments. A further development in the network meta-analysis is to use a Bayesian statistical approach, which provides a more flexible modelling framework to take into account heterogeneity in the evidence and complexity in the data structure. The aim of this paper is therefore to provide a nontechnical introduction to network meta-analysis for dental research community and raise the awareness of it. An example was used to demonstrate how to conduct a network meta-analysis and the differences between it and traditional meta-analysis. The statistical theory behind network meta-analysis is nevertheless complex, so we strongly encourage close collaboration between dental researchers and experienced statisticians when planning and conducting a network meta-analysis. The use of more sophisticated statistical approaches such as network meta-analysis will improve the efficiency in comparing the effectiveness between multiple treatments across a set of trials.

scholarly journals The versatility of generalizability theory as a tool for exploring and controlling measurement error

2014 ◽  
Vol 31 (2) ◽  
pp. 55-73 ◽  
Author(s):  
Sandra Johnson
Keyword(s):  
Measurement Error ◽  
Error Estimation ◽  
Generalizability Theory ◽  
Educational Assessment ◽  
Measurement Procedure ◽  
Estimation And Prediction ◽  
Generalizability Analysis ◽  
Many Sources

Measurement error arises from many sources in educational assessment. It is important to estimate the importance of this error, and, if appropriate, to seek ways to reduce it. Generalizability theory represents a powerful tool in this sense, allowing identifiable error contributions to be separately quantified, and measurement error to be estimated and even predicted in response to possible changes in the measurement procedure. The paper offers examples of generalizability analysis of numeracy attainment data deriving from the Scottish Survey of Achievement, with the aim of illustrating the versatility of the methodology for error estimation and prediction in this type of sample-based programme.

scholarly journals Validation of a measurement procedure for the assessment of the safety of buildings in urgent technical rescue operations

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 140
Author(s):  
Maria Alicandro ◽  
Giulio D’Emilia ◽  
Donatella Dominici ◽  
Antonella Gaspari ◽  
Stefano Marsella ◽  
...  
Keyword(s):  
Measurement Procedure ◽  
Test Cases ◽  
Emergency Situations ◽  
Standard Procedures ◽  
Set Up ◽  
Definition Of ◽  
Simplified Procedures ◽  
Different Characteristics ◽  
Future Work

This work would like to provide a preliminary contribution to the draft of standard procedures for the adoption of Total Stations by rescuers in emergency situations, so as to offer a reliable and effective support to their assessment activities. In particular, some considerations will be made regarding the effect of the number and positioning of monitoring points on the tilt determination of a building façade, in order to set up simplified procedures, which are quick and easy to implement in emergency situations, at the same time guaranteeing the reliability of the results. Two types of building will be taken into account as test cases, which have different characteristics in terms of height, distance and angle with respect to the Total Station. Some considerations will be made about the aspects to be explored in future work, for the calibration of the method as a whole and the definition of all the steps of a procedure for the evaluation of the safety of a building.

Effect of Niacin on Mitochondria of Allium Cepa Root Cells

1967 ◽  
Vol 25 ◽  
pp. 78-79
Author(s):  
M. Arif Hayat
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Hydrogen Transfer ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Nicotinamide Adenine ◽  
Root Tips ◽  
Root Cells ◽  
Transfer Processes ◽  
Standard Procedures ◽  
A Cell ◽  
Critical Interest

Although it is recognized that niacin (pyridine-3-carboxylic acid), incorporated as the amide in nicotinamide adenine dinucleotide (NAD) or in nicotinamide adenine dinucleotide phosphate (NADP), is a cofactor in hydrogen transfer in numerous enzyme reactions in all organisms studied, virtually no information is available on the effect of this vitamin on a cell at the submicroscopic level. Since mitochondria act as sites for many hydrogen transfer processes, the possible response of mitochondria to niacin treatment is, therefore, of critical interest.Onion bulbs were placed on vials filled with double distilled water in the dark at 25°C. After two days the bulbs and newly developed root system were transferred to vials containing 0.1% niacin. Root tips were collected at ¼, ½, 1, 2, 4, and 8 hr. intervals after treatment. The tissues were fixed in glutaraldehyde-OsO4 as well as in 2% KMnO4 according to standard procedures. In both cases, the tissues were dehydrated in an acetone series and embedded in Reynolds' lead citrate for 3-10 minutes.

Microstructure of Electro-Eroded Cemented Carbide Surfaces

1968 ◽  
Vol 26 ◽  
pp. 284-285
Author(s):  
V. N. Filimonenko ◽  
M. H. Richman ◽  
J. Gurland
Keyword(s):  
Surface Layer ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Standard Procedures ◽  
Face Centered ◽  
Diamond Paste ◽  
Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

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