Search

The editorial in "Frontiers in Neuroinformatics" discusses the importance of reproducibility in neuroscience research. It defines terms like repeatability, replicability, and reproducibility, emphasizing the need for independent verification of scientific findings. The editorial also highlights the role of open science practices, data sharing, and code transparency in ensuring research reproducibility. Various tools and software packages are introduced to support reproducible and replicable research in neuroscience. [Extracted from the article]

Radiomics, which integrates the comprehensive characterization of imaging phenotypes with machine learning algorithms, is increasingly recognized for its potential in the diagnosis and prognosis of oncological conditions. However, the repeatability and reproducibility of radiomic features are critical challenges that hinder their widespread clinical adoption. This review aims to address the paucity of discussion regarding the factors that influence the reproducibility and repeatability of radiomic features and their subsequent impact on the application of radiomic models. We provide a synthesis of the literature on the repeatability and reproducibility of CT/MR-based radiomic features, examining sources of variation, the number of reproducible features, and the availability of individual feature repeatability indices. We differentiate sources of variation into random effects, which are challenging to control but can be quantified through simulation methods such as perturbation, and biases, which arise from scanner variability and inter-reader differences and can significantly affect the generalizability of radiomic model performance in diverse settings. Four suggestions for repeatability and reproducibility studies are suggested: (1) detailed reporting of variation sources, (2) transparent disclosure of calculation parameters, (3) careful selection of suitable reliability indices, and (4) comprehensive reporting of reliability metrics. This review underscores the importance of random effects in feature selection and harmonizing biases between development and clinical application settings to facilitate the successful translation of radiomic models from research to clinical practice. [ABSTRACT FROM AUTHOR]

The Particle Measurement Programme Informal Working Group (PMP-IWG) coordinated a global interlaboratory study (ILS) on brake wear particle emissions with the participation of 16 testing facilities. Two articles present the main outcomes of the ILS: (I) Particulate matter mass (PM), and (II) Particle Number (PN) emissions. The test matrix covered a wide variety of brake systems and configurations. The tested disc brakes were found to emit PM2.5 and PM10 that varied between 0.8–4.0 mg/km and 2.2–9.5 mg/km per brake, respectively, depending on the type of brake and the applied testing load. The drum brake emitted much lower PM due to its enclosed nature. Almost 37–45% of the emitted PM falls in the fine particle size with this fraction being higher for the drum brake. On the other hand, almost 50–65% of the total brake mass loss falls in particle sizes larger than 10 μm or gets lost before being measured. The most important loss mechanisms for PM in the proposed layout are being discussed. Finally, the PM measurement variability and lab-to-lab reproducibility are investigated. [ABSTRACT FROM AUTHOR]

Ultrasound (US) is an increasingly prevalent and effective diagnostic modality for neuromuscular imaging. Gray-scale B-mode imaging has been the dominant US approach to evaluating nerves qualitatively or making morphometric measurements of nerves, providing important insights into pathological changes for conditions such as carpal tunnel syndrome. Among more recent ultrasound strategies, high-frequency ultrasound (often defined as >15 MHz for clinical applications), quantitative ultrasound and image textural analysis offer promising enhancements for improved and more objective approaches to nerve imaging. In this study, we evaluated the repeatability and reproducibility of backscatter coefficient (BSC) and imaging texture features extracted by gray-level co-occurrence matrices (GLCMs) in homogeneous tissue-mimicking reference phantoms and in median nerves in the wrists of healthy participants. We also investigated several practical sources of variability in the assessment of quantitative parameters, including influences of operators, and participant-to-participant variability. Overall, BSC- and GLCM-based outcomes are highly repeatable and reproducible after operator training, based on measurement of descriptive statistics, repeatability coefficient (RC) and reproducibility coefficient recommended by Quantitative Imaging Biomarker Alliance (QIBA RDC). GLCM parameters appear more reproducible and repeatable than BSC-based parameters in healthy participants in vivo. However, such variability noted here must be compared with the value ranges and variability of the results in pathological nerves, including median nerves afflicted by trauma, overuse syndromes such as carpal tunnel syndrome and after surgical repair. [ABSTRACT FROM AUTHOR]

Using optical coherence tomography angiography (OCTA), this study compared intrasession repeatability versus intersession reproducibility of macular vessel parameters in glaucoma and non-glaucoma subjects. 6 × 6 mm2 macular OCTA scans (Cirrus HD-OCT 5000) were acquired from glaucomatous and non-glaucomatous subjects as part of an observational, longitudinal study. Vessel area density (VAD) and vessel skeleton density (VSD) were calculated using research-based quantification software while perfusion density (PDZ) and vessel density (VDZ) were calculated using commercially developed software (Cirrus 11.0, Carl Zeiss Meditec). Intrasession repeatability and intersession reproducibility were determined using within-eye standard deviation (SW), within-eye coefficient of repeatability (CRW), within-eye coefficient of variation (CVW), and intraclass correlation coefficients (ICC). The intrasession repeatability and intersession reproducibility for macular OCTA parameters were similar to one another for both non-glaucomatous and glaucomatous eyes. Intrasession CVW from the non-glaucoma group (n = 73) was 1.097% for VAD, 1.007% for VSD, 2.980% for PDZ, and 2.714% for VDZ. Intersession CVW from the non-glaucoma group (n = 55) was 1.389% for VAD, 1.279% for VSD, 2.935% for PDZ, and 2.695% for VDZ. Intrasession CVW from the glaucoma group (n = 59) was 1.189% for VAD, 0.970% for VSD, 3.827% for PDZ, and 3.542% for VDZ. Intersession CVW from the glaucoma group (n = 45) was 1.412% for VAD, 1.132% for VSD, 3.915% for PDZ, and 3.654% for VDZ. Non-glaucomatous intrasession ICC ranged from 0.711 to 0.824, non-glaucomatous intersession ICC ranged from 0.649 to 0.762, glaucomatous intrasession ICC ranged from 0.710 to 0.853, and glaucomatous intersession ICC ranged from 0.661 to 0.827. Macular OCTA scans can be a useful tool in monitoring the longitudinal progression of glaucoma due to their high repeatability and reproducibility. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the repeatability and reproducibility (R&R) of quantitative ultrasound (QUS) estimates, specifically attenuation coefficient (AC) and backscatter coefficient (BSC), using the same Siemens 3000 clinical ultrasound scanner. Additionally, the purpose of this work is to detail the measurement and analysis methodology. Repeatability is closeness of agreement between measures obtained with the same method under same conditions (same sonographer and same transducer) and reproducibility is closeness of agreement between measures obtained with the same method under different conditions (different sonographers and/or different transducers). Calibrated phantoms were scanned by two sonographers using two transducers in each session for multiple sessions over a period of four months. The phantom scans occurred as part of a clinical QUS liver study in human research participants spanning a spectrum of obesity and liver disease severity. The scanner was adjusted in each participant to obtain the highest quality liver B-mode images prior to acquiring data from the phantoms for which no scanner adjustments were made. The R&R were analyzed and estimated using the unweighted sums of squares ANOVA approach by applying two random effect models. The measurement variance caused by repeatability and reproducibility is small (AC: 2.4- 3.2×10-4 [dB/cm-MHz]2; 10log10BSC: 0.23-0.27 dB2 ). The reproducibility variance is statistically significantly lower than the repeatability variance. The total R&R was not influenced by phantom properties over a wide range representing those found in liver in vivo.

AASHTO has provisionally endorsed the use of a three-wheel polishing device (TWPD) for polishing and the dynamic friction tester (DFT) for measuring the friction of the coarse aggregates used in hot mix asphalt (HMA). Despite ample studies showing the feasibility of such a system for HMA specimens, research efforts related to quantifying the coarse aggregates that are used in those mixes have been less common. The results of a study to accelerate the test and to decrease the tedium of specimen preparation for aggregates are reported here. Three identical TWPD devices that complied with the AASHTO provisional specification were fabricated. A new specimen preparation method was introduced to reduce the associated time and cost. Several operational parameters that can impact the repeatability and reproducibility of the process, such as tire type and tread condition, specimen preparation, and DFT rubber pad thickness, were investigated. This study verified that the TWPD/DFT test method can delineate the polishing/friction performance of different aggregates with acceptable repeatability and reproducibility. The TWPD/DFT test time and cost can potentially be decreased considerably by using the proposed practical and analysis modifications. [ABSTRACT FROM AUTHOR]

A new approach to identify and diagnose the quality of extensive and multivariate data is presented, using the gage repeatability and reproducibility (GR&R) study through the weighting of rotated factor scores. The proposal uses axis rotation to improve the explanation and interpretations of latent information, providing a statistically appropriate alternative when dealing with two or more correlated data sets. To analyze data with a significant variance-covariance structure, factor analysis (FA) is applied for calculating the eigenvalues and extracting of the rotated scores. Once obtained, these scores are then weighted with their respective eigenvalue for each factor. This procedure results in a single response vector, which is capable of properly interpreting all of the quality responses analyzed. To illustrate an application of the method, a real data set from a resistance spot welding process is selected, and two different types of rotation are compared. The proposed method provided an output that contemplated all of the significant variability of the data in a unique and significant way. In addition, the method enabled a reduction in the data dimensionality, thus minimizing the time for analysis and computational effort.

Use of sensor data has been increasingly common in recent years, yet there is still a knowledge gap in evaluating the precision of traffic sensor data being used in traffic analyses for developing a transportation management plan. This paper fills this gap by exploring a new approach to evaluating the level of precision of large-scale traffic sensor data. The proposed analytical framework incorporates a spatiotemporal domain for the purpose of projecting spatiotemporal characteristics of the data into a repeatability and reproducibility (R&R) study. The main finding of this study is that the proposed framework is effective in examining the precision level of large-scale data spatiotemporally. The proposed framework would be useful for researchers and practitioners to benchmark precision measurements of traffic sensor data in a way to gather quality data and avoid any potential biased result of deeper traffic analyses. [ABSTRACT FROM AUTHOR]

In a process that has multiple correlated characteristics, it is more appropriate to use multivariate techniques. This study proposes a multivariate gage repeatability and reproducibility (GR&R m) approach based on weighted principal component factor analysis and confidence ellipses for the number of distinct categories (ndc). The method was applied to the textured fiber bobbins process to analyze the measurement system of a leading textile company in Brazil, at its factory responsible for 15% of its total production. Among quality characteristics, measurements of mass, density, and diameter of the bobbins were analyzed. The analysis is divided into two main groups: the initial situation of the measurement system, and the verification measurements taken after calibration adjustments. The adjustments were made to the calibration of the equipment and significantly reduced the variability of the measurements, with the proposed method providing adequate identification of the variability, describing the confidence ellipses of the ndc in a non-overlapping manner, and classifying the measurement system as acceptable. In this study, it was possible to verify that the proposed strategy yields satisfactory results, minimized the dimensionality of the data evaluated, reduced the time and isolated analyses considering the variance-covariance structure. Consequently, it was possible to validate the company's measurement system, bringing greater reliability to actions performed by its process control division. • A multivariate measurement system for textured fiber bobbins was applied. • A GR&R study based on weighted factor scores was proposed. • A confidence ellipses for the number of distinct categories was proposed. • The method presents adequate results and minimized the dimensionality of the data. • The results show an improvement and a higher reliability in the process. [ABSTRACT FROM AUTHOR]

• Traditional GR&R studies are limited to determine the source of measuring error. • Proposed new indicators detect both repeatability and reproducibility errors. • A stainless steel cladding process on surfaces of carbon steel were assessed. • Empirical results showed that the proposal outperformed literature method. Measurement system analysis has a pivotal role in assessing the measuring error when conducting empirical studies. Gage Repeatability and Reproducibility (GR&R) studies are classic methods applied to evaluate measurement system adequacy for a particular application. However, previous published studies are limited to determine the source of measuring error related to not only reproducibility but also repeatability. Hence, the objective of this research is to propose new indicators for measurement error detection due to both repeatability and reproducibility variation in GR&R studies. These indicators were calculated using standardized scores from the analysis of variance. The proposed procedure has been applied not only to literature data but also to a stainless steel cladding process on surfaces of carbon steel. While literature method has detected only reproducibility error, the proposed procedure were able to detect both reproducibility and repeatability sources of measuring error. [ABSTRACT FROM AUTHOR]

The quality and reliability in additive manufacturing is an emerging area. To ensure process quality and reliability, the influence of all process parameters and conditions needs to be understood. The product quality and reliability characteristics, i.e., dimensional accuracy, precision, repeatability, and reproducibility are mostly affected by inherent and systematic manufacturing process variations. This paper presents research on dimensional quality and distortion analysis of AlSi10Mg thin-walled parts developed by a selective laser melting technique. The input process parameters were fixed, and the impact of inherent process variation on dimensional accuracy and precision was studied. The process stability and variability were examined under repeatability and reproducibility conditions. The sample length (horizontal dimension) results revealed a 0.05 mm maximum dimensional error, 0.0197 mm repeatability, and 0.0169 mm reproducibility. Similarly, in sample height (vertical dimension) results, 0.258 mm maximum dimensional error, 0.0237 mm repeatability, and 0.0863 mm reproducibility were observed. The effect of varying design thickness on thickness accuracy was analyzed, and regression analysis performed. The maximum 0.038 mm error and 0.018 mm standard deviation was observed for the 1 mm thickness sample, which significantly decreased for sample thickness ≥2 mm. The % error decreased exponentially with increasing sample thickness. The distortion analysis was performed to explore the effect of sample thickness on part distortion. The 0.5mmthickness sample shows a very high distortion comparatively, and it is reduced significantly for >0.5 mm thickness samples. The study is further extended to examine the effect of solution heat treatment and artificial aging on the accuracy, precision, and distortion; however, it did not improve the results. Conclusively, the sample dimensions, i.e., length and height, have shown fluctuations due to inherent process characteristics under repeatability and reproducibility conditions. The ANOVA results revealed that sample length means are not statistically significantly different, whereas sample height means are significantly different. The horizontal dimensions in the xy-plane have better accuracy and precision compared to the vertical dimension in the z-axis. The accuracy and precision increased, whereas part distortion decreased with increasing thickness. [ABSTRACT FROM AUTHOR]

This paper aimed to compare the performance of multivariate GR&R (gage repeatability and reproducibility) studies based on PCA (principal component analysis) and Manova (multivariate analysis of variance) methods. To estimate the multivariate gauge index, geometric and arithmetic means have been implemented with and without weighting strategies. Bootstrap confidence interval based on BCa (bias-corrected and accelerated) method has been adopted to determine multivariate gauge index adequacy. This confidence interval was calculated for the mean of univariate gauge indices estimated from each quality characteristic. The result analyses have shown that weighted approaches provided the best estimates of gauge index in multivariate GR&R studies.

Muscle strength is an important clinical outcome in rehabilitation and sport medicine, but options are limited to expensive but accurate isokinetic dynamometry (IKD) or inexpensive but less accurate hand-held dynamometers (HHD). A wearable, self-stabilizing, limb strength measurement device (LSMD) was developed to fill the current gap in portable strength measurement devices. The purpose of this study was to evaluate the reliability and validity of the LSMD in healthy adults. Twenty healthy adults were recruited to attend two strength testing sessions where elbow flexor and extensor strength was measured with the LSMD, with HHD and with IKD in random order, by two raters. Outcomes were intra-rater repeatability, inter-rater reproducibility and inter-session reproducibility using intra-class correlation coefficients (ICC). Limits of agreement and weighted least products regression were used to test the validity of the LSMD relative to the criterion standard (IKD), and calibration formulas derived to improve measurement fidelity. ICC values for the LSMD were >0.90 for all measures of reliability and for both muscle groups, but over-predicted extensor strength and under-predicted flexor strength. Validity was established by transforming the data with the criterion standard-based calibration. These data indicate that the LSMD is reliable and conditionally valid for quantifying strength of elbow flexors and extensors in a healthy adult population.

Passive intermodulation (PIM) is a critical measurement for radio frequency (RF) communication networks. Yet PIM measurement inherently has very poor repeatability, which makes product assessment unreliable. The RF industry struggles with the issue since there are no known solutions. With the increasing demand for low-PIM performance, there are pressing demands to address the challenge. Two fundamental problems make traditional gage R&R study invalid for PIM: (1) PIM in nature is unstable and unrepeatable; (2) PIMmeasurement has inherently inconstant variance at differentPIMlevels, which is primarily due to limited capability of PIM analyzer. This resulted in several less-known issues significantly impacting the estimation of PIM test repeatability, including sample selection, one-sided spec and differences between test R&R and gage R&R. The paper proposed two fundamental changes when studyingR&Rof PIM test or tests in general violating constant variance assumptions: (1) sample selection; (2) what measurement to use to better estimate and represent the test repeatability. Special sampling is proposed to minimize the impact of inconstant variance. A more direct R&R measurement, margin of error (MOE), also known as study variation, is proposed to replace traditional gage R&R metrics to more meaningfully represent PIM test R&R. Several statistically based techniques to improve the repeatability and reliability of PIM measurement are also discussed. The study and proposed solutions apply to not only PIM test but also tests in general violating constant variance assumptions. [ABSTRACT FROM AUTHOR]

The quality and reliability in additive manufacturing is an emerging area. To ensure process quality and reliability, the influence of all process parameters and conditions needs to be understood. The product quality and reliability characteristics, i.e., dimensional accuracy, precision, repeatability, and reproducibility are mostly affected by inherent and systematic manufacturing process variations. This paper presents research on dimensional quality and distortion analysis of AlSi10Mg thin-walled parts developed by a selective laser melting technique. The input process parameters were fixed, and the impact of inherent process variation on dimensional accuracy and precision was studied. The process stability and variability were examined under repeatability and reproducibility conditions. The sample length (horizontal dimension) results revealed a 0.05 mm maximum dimensional error, 0.0197 mm repeatability, and 0.0169 mm reproducibility. Similarly, in sample height (vertical dimension) results, 0.258 mm maximum dimensional error, 0.0237 mm repeatability, and 0.0863 mm reproducibility were observed. The effect of varying design thickness on thickness accuracy was analyzed, and regression analysis performed. The maximum 0.038 mm error and 0.018 mm standard deviation was observed for the 1 mm thickness sample, which significantly decreased for sample thickness ≥2 mm. The % error decreased exponentially with increasing sample thickness. The distortion analysis was performed to explore the effect of sample thickness on part distortion. The 0.5 mm thickness sample shows a very high distortion comparatively, and it is reduced significantly for >0.5 mm thickness samples. The study is further extended to examine the effect of solution heat treatment and artificial aging on the accuracy, precision, and distortion; however, it did not improve the results. Conclusively, the sample dimensions, i.e., length and height, have shown fluctuations due to inherent process characteristics under repeatability and reproducibility conditions. The ANOVA results revealed that sample length means are not statistically significantly different, whereas sample height means are significantly different. The horizontal dimensions in the xy-plane have better accuracy and precision compared to the vertical dimension in the z-axis. The accuracy and precision increased, whereas part distortion decreased with increasing thickness.

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper presents results related to assessment of the repeatability and reproducibility of the measurement test setup for determination the relative value of the shielding effectiveness coefficient of the industrial connectors. The construction of the proposed test setup, the measurement method and the procedure for the analysis of measurement results were described. To determine the value of the repeatability and reproducibility coefficient, the two-way analysis of variance was used, which additionally allows for an assessment of the influence of individual sources of variance. The measurements and their analysis were conducted for several frequencies in the range up to 1 GHz. Additionally, the expanded measurement uncertainty, including the test setup and instruments uncertainty was estimated. [ABSTRACT FROM AUTHOR]

• Repeatability and reproducibility of MR-linac DWI sequences were within 2.22% and 4.37% of MR sim DWI sequences, respectively. • Of the MR-linac DWI sequences, SPLICE generally outperformed EPI and TSE in terms of repeatability/reproducibility, ADC bias, and SNR. • Spatial dependence of phantom ADC values was observed for the MR-linac but not for the MR sim, which may be due to uncorrected gradient non-linearities. • MR-linac DWI sequences are robust and worthy of further clinical evaluation for treatment response assessment and biological image-guided ART in HNC. Diffusion-weighted imaging (DWI) on MRI-linear accelerator (MR-linac) systems can potentially be used for monitoring treatment response and adaptive radiotherapy in head and neck cancers (HNC) but requires extensive validation. We performed technical validation to compare six total DWI sequences on an MR-linac and MR simulator (MR sim) in patients, volunteers, and phantoms. Ten human papillomavirus-positive oropharyngeal cancer patients and ten healthy volunteers underwent DWI on a 1.5 T MR-linac with three DWI sequences: echo planar imaging (EPI), split acquisition of fast spin echo signals (SPLICE), and turbo spin echo (TSE). Volunteers were also imaged on a 1.5 T MR sim with three sequences: EPI, BLADE (vendor tradename), and readout segmentation of long variable echo trains (RESOLVE). Participants underwent two scan sessions per device and two repeats of each sequence per session. Repeatability and reproducibility within-subject coefficient of variation (wCV) of mean ADC were calculated for tumors and lymph nodes (patients) and parotid glands (volunteers). ADC bias, repeatability/reproducibility metrics, SNR, and geometric distortion were quantified using a phantom. In vivo repeatability/reproducibility wCV for parotids were 5.41%/6.72%, 3.83%/8.80%, 5.66%/10.03%, 3.44%/5.70%, 5.04%/5.66%, 4.23%/7.36% for EPI MR-linac , SPLICE, TSE, EPI MR sim , BLADE, RESOLVE. Repeatability/reproducibility wCV for EPI MR-linac , SPLICE, TSE were 9.64%/10.28%, 7.84%/8.96%, 7.60%/11.68% for tumors and 7.80%/9.95%, 7.23%/8.48%, 10.82%/10.44% for nodes. All sequences except TSE had phantom ADC biases within ± 0.1x10-3 mm2/s for most vials (EPI MR-linac , SPLICE, and BLADE had 2, 3, and 1 vials out of 13 with larger biases, respectively). SNR of b = 0 images was 87.3, 180.5, 161.3, 171.0, 171.9, 130.2 for EPI MR-linac , SPLICE, TSE, EPI MR sim , BLADE, RESOLVE. MR-linac DWI sequences demonstrated near-comparable performance to MR sim sequences and warrant further clinical validation for treatment response assessment in HNC. [ABSTRACT FROM AUTHOR]

The effect of training instruction, whether presented as the manufacturer′s printed instructions, a short video training session specific to the product, or as a one-on-one training session was evaluated using four hearing protection devices with eight groups of subjects. Naïve subjects were recruited and tested using three different forms of training: written, video, and individual training. The group averages for A-weighted attenuation were not statistically significant when compared between the video or the written instruction conditions, regardless of presentation order. The experimenter-trained A-weighted attenuations were significantly greater than the written and video instruction for most of the protectors and groups. For each earplug, the noise reduction statistic for A-weighting (NRS A ) and the associated confidence intervals were calculated for the 80 th and 20 th percentiles of protection. Across subject groups for each protector, the differences between NRS A ratings were found to be not statistically significant. Several comparisons evaluating the order of testing, the type of testing, and statistical tests of the performance across the groups are presented.

Copyright of Acta Scientiarum: Technology is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Optical coherence tomography angiography (OCTA) has increasingly become a clinically useful technique in ophthalmic imaging. We evaluate the repeatability and reproducibility of blood perfusion in the optic nerve head (ONH) measured using optical microangiography (OMAG)-based OCTA. Ten eyes from 10 healthy volunteers are recruited and scanned three times with a 68-kHz Cirrus HD-OCT 5000-based OMAG prototype system (Carl Zeiss Meditec Inc., Dublin, California) centered at the ONH involving two separate visits within six weeks. Vascular images are generated with OMAG processing by detecting the differences in OCT signals between consecutive B-scans acquired at the same retina location. ONH perfusion is quantified as flux, vessel area density, and normalized flux within the ONH for the prelaminar, lamina cribrosa, and the full ONH. Coefficient of variation (CV) and intraclass correlation coefficient (ICC) are used to evaluate intravisit and intervisit repeatability, and interobserver reproducibility. ONH perfusion measurements show high repeatability [CV ≤ 3.7% (intravisit) and ≤ 5.2% (intervisit)] and interobserver reproducibility (ICC ≤ 0.966) in all three layers by three metrics. OCTA provides a noninvasive method to visualize and quantify ONH perfusion in human eyes with excellent repeatability and reproducibility, which may add additional insight into ONH perfusion in clinical practice. [ABSTRACT FROM AUTHOR]

Measurement error is an unavoidable source of variation in any decision-making process based on experimental research. Components of variation due to measurement system and manufacturing process must be estimated and special causes of variation should be reduced whenever possible. GR&R (gage repeatability and reproducibility) studies quantify these sources of variation by using analysis of variance. The main contribution of this paper is to conjoin GR&R and the multiple comparisons method of Scott-Knott in order to help practitioners identifying special causes of variation in empirical studies. Stainless steel cladding process has been evaluated to validate the proposed procedure. The experimental findings have shown that the well-structured method based on Scott-Knott test was effective in indicating the source of error due to reproducibility. [ABSTRACT FROM AUTHOR]

In the evaluation of process capability, gauge measurement errors usually distort the measured data yielding two dissimilar capability indices, particularly, the actual and the observed process capability indices ( AC p and OC p ). Gauge measurement errors result in underestimation of the actual process capability, consequently, the variance of gauge errors has to be assessed to better chart the relationship between the AC p and OC p . The different variance components of a measurement system can be assessed by a gauge repeatability and reproducibility (GR&R) study. This paper presents novel relationships between the AC p and OC p by means of a signal-to-noise ratio ( SNR ) model. The probability density functions of both indices will be presented in terms of SNR and a procedure to find the critical values of AC p and OC p is established. In contrast to literature studies, a measurement system can now be described by a novel α–β characteristic curve. Different SNR values will result in different α – β curves, hence, the acceptance of a measurement system depends on the specified significance values of α and β and not solely on strict SNR values. Since measured data yields two different AC p and OC p distributions, type I and type II error analysis can be performed. Different case studies are presented to validate the resulting relationships and distributions. [ABSTRACT FROM AUTHOR]

Measurement system capability analysis is to determine whether the measurement system is capable for use in quality control. The existing research has been extended from univariate to multivariate cases. Two approaches, the multivariate analysis of variance (MANOVA) and the weighted principal components (WPC), were advocated in literature. The MANOVA method is constructed based on the volume ratio that treats the volume of constant-density contours as the variability estimations. However, it ignores the fact that the relative position change of multivariate measurement errors could affect the measurement system capability. The WPC method uses dimension reduction to reduce the complexity but is unable to build the precision-to-tolerance ratio because it does not include tolerance. In this paper, we propose a modified-region-based method to compute the precision-to-tolerance ratio, the percent of repeatability and reproducibility, and the signal-to-noise ratio. This method also incorporates the variance-covariance structure of the measurement errors when dealing with the constant-density contours of tolerances, total variation, and process variation. The performance of the modified-region-based method is evaluated based on a dataset from the literature and a set of relevant simulation. The proposed method proves to be effective compared with other methods.Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This work analyzes data from an experimental study on façade sound insulation, consisting of independent repeated measurements executed by different laboratories on the same residential building. Mathematically, data can be seen as functions describing an acoustic parameter varying with frequency. The aim of this study is twofold. On one hand, considering the laboratory as the grouping variable, it is important to assess the within-group and between-group variability in the measurements. On the other hand, in building acoustics, it is known that sound insulation is more variable at low frequencies (from 50 to 100Hz), compared with higher frequencies (up to 5000Hz), and therefore, a multilevel functional model is employed to decompose the functional variance both at the measurement level and at the group level. This decomposition also allows for the ranking of the laboratories on the basis of measurement variability and performance at low frequencies (relative high variability) and over the whole spectrum. The former ranking is obtained via the principal component scores and the latter via an original Bayesian extension of the functional depth. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• Flash-pulse thermographic inspection of carbon-fiber composites. • Infrared non-destructive testing of materials. • Repeatability and reproducibility of non-destructive inspection. • Gage R&R analysis based on contrast and size of indications. Thermographic flash-pulse inspection is a popular technique of non-destructive testing (NDT) of carbon-fiber composites. Despite of an automation of the NDT methods, most of them are based on a visual inspection of indications and results of the inspections are thus influenced by the skills of operators. Repeatability and reproducibility (R&R) analysis of these inspections are therefore more important than in the case of exact gauge-type methods. This study was focused on statistical evaluation of flash pulse inspection. Space hardware representative carbon-fiber composite samples with 50 artificial defects were used as reference samples, which were independently inspected by three operators in two independent runs.Gauge R&R study was performed based on contrast to noise ratio and size of defects indications. It was determined, that, at certain conditions, a total Gage R&R variability 23% and 45% can be achieved for the diameter and the contrast to noise ratio evaluation, respectively. [ABSTRACT FROM AUTHOR]

Material properties are crucial input parameters for the analysis of heat, air and moisture transfer phenomena in built environment. However, many round robin tests reveal that the measurements on material properties – especially hygric properties – have poor reproducibility. Thus the measurement and data analysis methods should be questioned, and the currently available databases for material properties are not perfectly reliable. In this paper we aim at analyzing the material errors, repeatability errors, between-lab errors and reproducibility errors involved in the determination of hygric properties of porous building materials. The same materials as those used in the EC HAMSTAD project – autoclaved aerated concrete, calcium silicate board and ceramic brick – are chosen as target materials in our tests to facilitate error analysis. Static gravimetric tests, cup tests, capillary absorption tests, vacuum saturation tests and pressure plate tests have been repeated three times under repeatability conditions. Then the experimental results are analyzed in combination with the EC HAMSTAD report to calculate various errors. Results show that different materials have different heterogeneity errors, which can hardly be avoided. Moreover, in general these tests have excellent repeatability, indicating that under proper control the tests themselves are trustworthy. However, the large between-lab errors and the subsequent poor reproducibility demonstrate that in different labs the experimental procedures, condition controls, as well as data processing methods can deviate significantly. As a result, stricter and more detailed instructions are needed to improve the reproducibility of the tests for determining the hygric properties of porous building materials. [ABSTRACT FROM AUTHOR]

Purpose To assess the repeatability, reproducibility, and agreement of central corneal thickness (CCT) measured by non-contact Fourier domain optical coherence tomography (FD-OCT; OptoVue) with the other two contact devices, ocular response analyzer (ORA; Reichert Ophthalmic Instruments) and Ultrasound Pachymetry (USP; DGH Technologies). Methods This observational cross-sectional study measured CCT sequentially using FD-OCT, ORA and USP. The first 16 volunteers (32 eyes) received three measurements by two independent examiners in a single session to determine intra-observer repeatability and inter-observer reproducibility. An additional 27 volunteers (54 eyes) received one measurement by the same examiner. The measurements of all 86 eyes were analyzed for the difference, correlation, and agreement among the three devices. Results FD-OCT measured the thinnest while USP measured the thickest CCT (548.6 ± 28.3 μm, 556.9 ± 28.8 μm, and 560.0 ± 28.8 μm by FD-OCT, ORA, and USP, respectively, p < 0.001). The mean differences (lower/upper limit of agreement) for CCT measurements were 8.4 ± 7.6 μm (−6.5/23.2) between ORA and FD-OCT, 11.4 ± 7.3 μm (−2.8/25.7) between USP and FD-OCT, and 3.1 ± 5.1 μm (−6.9/13.1) between ORA and USP. The intra-class correlation coefficients were above 0.98 for all tested groups. FD-OCT had the lowest intra-examiner variability (coefficient of repeatability of 0.64%) and lowest inter-examiner variability (coefficient of reproducibility of 1.16%). Conclusion FD-OCT, ORA, and USP demonstrated good inter-observer reproducibility and intra-observer repeatability. The three measurements were highly correlated; however, systematic differences between the three tested devices did exist. FD-OCT was a reliable and examiner-independent method in CCT measurement. [ABSTRACT FROM AUTHOR]

Highlights: [•] We analyze measurement systems with multiple correlated characteristics. [•] We use a multivariate approach for gage repeatability and reproducibility studies. [•] We propose four new indexes for assessing multivariate measurement systems. [•] We use data from a turning process and literature data with different correlations. [•] The performance of the literature index was compared to the proposed indexes. [Copyright &y& Elsevier]

Abstract: In sensory analysis attributes are measured on samples based on human judgment. The ability to detect differences is essential when selecting a panelist, as well as the repeatability in assessments and the agreement among panelists (or reproducibility), which is our definition of panel consistency. Our goal in this paper is to identify an efficient method to compare evaluation profiles from panelists measuring a given sensory attribute on different samples, assessing the panel’s consistency. For that we investigate two methods available in the literature – consonance analysis (Dijksterhuis, 1995), and repeatibility and reproducibility analysis (Rossi, 2001) – and propose a new method, based on the internal consistency test and the calculation of the Cronbach’s alpha coefficient (Cronbach, 1951). We tested our proposition using a dataset from a case study in which beef cubes in stew, used as combat ration by the American Army, are characterized by a sensory panel using the Spectrum protocol. Different product formulations based on military specifications yielded eight samples evaluated by nine panelists in quadruplicate. Twenty-four sensory attributes were assessed by the panelists. Results pointed to the Cronbach’s alpha coefficient as best among the methods tested, which is justified threefold: (i) it allows identifying attributes better understood by panelists, (ii) it gives a ranking of panelists according to their consensus with the rest of the panel, and (iii) it is analytically simpler in comparison with other methods. [Copyright &y& Elsevier]

In Measurement System Analysis a relevant issue is how to find confidence intervals for the parameters used to evaluate the capability of a gauge. In literature approximate solutions are available but they produce so wide intervals that they are often not effective in the decision process. In this article we introduce a new approach and, with particular reference to the parameter γR, i.e., the ratio of the variance due to the process and the variance due to the instrument, we show that, under quite realistic assumptions, we obtain confidence intervals narrower than other methods. An application to a real microelectronic case study is reported. [ABSTRACT FROM AUTHOR]

The aims of this study were to establish a normal reference range (mean ± 2 SD) and assess reliability of renal dimensions obtained using transabdominal ultrasonography in Thoroughbred horses ( n = 7). A minimum of three ultrasonographic cineloops were obtained from each intercostal space and the left paralumbar fossa by two observers daily for three consecutive days. Renal length, width, and thickness and cortex, medulla, and pelvic dimensions were obtained. Measurements were undertaken by both observers, who were unaware of prior measurements, to assess reproducibility and measured on three separate occasions to evaluate short-term measurement repeatability. Measurements from images obtained by both operators were compared to evaluate image repeatability. The left kidney was consistently identified in the left 15th-17th intercostal space and the paralumbar fossa with maximal length in the 16th intercostal space (12.7 ± 2.0 cm) and maximal width in the paralumbar fossa (7.9 ± 1.1 cm). The right kidney was consistently identified in the right 15th-17th intercostal space with maximal length and maximal width in the 15th intercostal space (16.0 ± 0.7 cm and 7.9 ± 1.0 cm). Reproducibility, image repeatability, measurement repeatability were good to excellent, although were less good for the smaller structures. There were no differences in renal dimensions between horses. Overall renal ultrasonography was reliable and a normal reference range for Thoroughbred horses was established. Renal dimensions vary between rib spaces. As repeatability and reproducibility were excellent for renal length and width, it may be prudent to use those measurements in rib spaces where parameters were maximal. [ABSTRACT FROM AUTHOR]

Although some measurements can be made on any scale (including a continual scale), cost and speed considerations sometimes tip the scales toward using ordinal measurements. This paper presents a way to evaluate classical metrological characteristics, such as error, uncertainty and precision of single and repeated measurements based on the legitimate basic operations for ordinal data. The only legitimate measurement operations among ordinal variables are limited to equal or greater than/less than, the usual assessment measures such as average, standard deviation cannot be applied. Consequently, in order to receive reliable results and draw valid conclusions from ordinal measurements it is essential to develop and use only the appropriate methods. [ABSTRACT FROM AUTHOR]

Measurement systems capability analysis aims to test if the variability of a measurement system is small relative to the variability of a monitored process. At present some open questions are related both to the interpretation of the critical values of the indices typically used by practitioners to assess the capability of a gauge and to the choice of the size of the experimental design to test the repeatability and the reproducibility of the measurement process. In this paper, starting from the misclassification rates of a measurement system, we present a solution to these issues. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We describe a methodology for the assessment of the repeatability and reproducibility (R&R) of measurement systems that measure on a binary scale, such as pass-fail inspections. We focus on the situation where no reference values can be obtained for the objects in the experiment and consequently model the results of the R&R experiment as a latent class model. We provide estimators based on the maximum likelihood approach and the method of moments, and compare their properties. We also give guidelines for model checking and recommendations for sample sizes. The methodology is illustrated by an example. [ABSTRACT FROM AUTHOR]

Copyright of Medycyna Pracy is the property of Instytut Medycyny Pracy im. Jerzego Nofera and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)