Inter-rater reliability | EPFL Graph Search

In statistics, inter-rater reliability (also called by various similar names, such as inter-rater agreement, inter-rater concordance, inter-observer reliability, inter-coder reliability, and so on) is the degree of agreement among independent observers who rate, code, or assess the same phenomenon. Assessment tools that rely on ratings must exhibit good inter-rater reliability, otherwise they are not valid tests. There are a number of statistics that can be used to determine inter-rater reliability. Different statistics are appropriate for different types of measurement. Some options are joint-probability of agreement, such as Cohen's kappa, Scott's pi and Fleiss' kappa; or inter-rater correlation, concordance correlation coefficient, intra-class correlation, and Krippendorff's alpha. Concept There are several operational definitions of "inter-rater reliability," reflecting different viewpoints about what is a reliable agreement between raters. There are three operational

Predrilled locking compression plate is more accurate than tension band wiring in restoring articular geometry of the ulnar greater sigmoid notch after olecranon Chevron osteotomy

Alexandre Terrier, Frédéric Vauclair

Introduction: The olecranon Chevron osteotomy (OCO) is commonly used to approach complex intraarticular fractures of the distal humerus. Predrilled tension band wiring (TBW) has historically been used to fix OCO. However, clinical outcomes are burdened by secondary loss of reduction and up to 21.3% non-union rates. The biomechanical stability of anatomic locking compression plate (LCP) was reported to be superior to TBW in olecranon fracture fixation. We hypothesised that this implant may also be superior to TBW in the anatomic reconstruction of the articular surfaces of the ulnar greater sigmoid notch after OCO by predrilling the holes of the angular stable plate with the threaded drill guide prior to osteotomy. Materials and methods: Lateral standardised and calibrated radiographs of twenty synthetic ulnar bones were obtained using a custom-made holder prior to preparation by a senior orthopaedic trauma surgeon. Ten specimens were then predrilled using the threaded drill bit guide of an olecranon LCP, while the other ten samples were predrilled with two 1.6 mm Kirschner wires. A distal "V" OCO was performed using a 0.6 mm oscillating saw. After repositioning and fixation with the corresponding device, lateral radiographs were repeated. Two independent observers used the TraumaCad planning software to document the articular geometry of the ulnar greater sigmoid notch pre- and postoperatively. The diameter of the best-fitting circle (diameter), the distance between the tip of the coronoid and the olecranon processes (distance) and the maximum articular depth were measured. Results: With the TBW technique, after OCO and fixation, all three postoperative measurements were significantly (p = 0.13). Inter and intra-observer measurement reliability was strong to very strong (intraclass correlation coefficients >= 0.793) for all three variables. Conclusion: Our study reveals that the predrilled LCP technique is more accurate than the predrilled TBW in restoring the anatomic articular geometry of the ulnar greater sigmoid notch after OCO. (C) 2020 Elsevier Ltd. All rights reserved.

ELSEVIER SCI LTD2020

Vieillissement et fiabilité des parcs de poteaux bois des réseaux de lignes aériennes

Yann Benoit

The reliability of new overhead electric and telecommunication lines depends principally on the quality of their support structures. These structures are generally made of wood, metal or concrete. The complexity of a natural substance such as wood requires a thorough analysis of the various factors that influence its overall quality. In the case of wood poles, such factors include initial forest growth pattern, the species of wood and its preservative treatment, ageing characteristics, and its various mechanical defects such as knots, cracks etc. The accumulation of knowledge on the effect of the various variables that contribute to the overall quality of a wood support structure permits an optimum use of such a resource. For example, less variability and higher strength of wood support structures permits optimum loading and spacing between structures, thus reducing the number needed in a specific length of an overhead line. If one assumes that in Western Europe 1 wood pole is employed for every 2 inhabitants, and that this proportion increases in less densely populated countries such as the US and Scandinavia, the economics of optimum use of wood as a resource soon become apparent. In less developed countries, the proportions and the economics vary depending on the natural resources such as wood that they employ. The goal of this research is to establish, thanks to non destructive evaluations, a general ageing probabilistic law of the wooden pole based on two distinguished laws: one on the new pole in studying the influence of a grading of the bad elements based on a normal law: "left-truncation of a normal distribution", point 1; and another one based on the in-field wooden pole in exploiting the different parameters such as: the age of the pole, its chemical treatment, its species, its knots etc. in order to define the pole's damage law, point 2. Statistical distribution law of the new wooden pole after grading by non destructive sorting (ultrasounds) of the high mechanical performances supports: This new distribution law is a Gaussian law or evolves to a Log or Weibull's law with 3 parameters according to the inspected species. This grading allows a revalorization of the properties of the new poles and of the design values while guaranteeing an index of reliability required by the design standards, or in improving directly this nominal reliability (economic gain and reliability gain). Statistical distribution law of an aged in-field population (20-50 years old) approached by a bi-modal law which depends on: The distribution law of the new component (see point 1) and its minimal extreme law, which is asymmetrical, for an observation on 50 years. The statistical distribution at the time t of the residual mechanical performances of a group of supports making a local net, evaluated by non destructive methods. The non destructive evaluation is based on the measurements of physical variables (density, biological moisture content) and some descriptive variables from natural origins (diameter, knots, cracks...) and from accidental origins (diameter reduction, lightning cracks...). The statistical distribution at the time t is then obtained on the basis of a model of multivariate non destructive evaluation, generalized to the whole of species and treatments. This model is the other concrete goal to reach in this thesis. As a conclusion, the research demonstrates the influence and the interaction of the new pole grading (distribution at t0) on the modelisation of the distribution at ti (multivariate non destructive model). The data used for the mentioned modelisations come from a significant international database with a large amount of inspected wood poles and with studied cases. This database is the synthesis of about 15 years of research and development leaded by IBOIS-EPFL and its international partners. The probabilistic approaches are then validated by a huge database allowing thus to be directly exploitable. On this basis, all the standards dealing with the new poles and dealing with the controls and maintenances of a wooden pole networks, could be re-examined for a double gain: Concerning the economy: by increasing the capacity of the new poles profiting of an objective quality assurance, and by increasing the life time of the in-field pole, in knowing how to purge only the ones which are under the critical threshold of damage Concerning the reliability: by increasing the reliability of the network from the stage "new pole", by eliminating the weakest components, and by maintaining this reliability during all the life time of the network thanks to a cyclic preventive maintenance (every 5 to 8 years) and the replacement of only the weakened poles.

EPFL2004

Auto-tuning deep forest for shear stiffness prediction of headed stud connectors

Yuqing Liu

The shear stiffness of headed stud connector is a critical parameter for the calculation of deflection and inter-facial shear force for steel-concrete composite structure. Thus, this study presented a promising data-driven model auto-tuning Deep Forest (ATDF) to precisely predict the stud shear stiffness, where the novel Deep For-est algorithm is integrated with the Sequential Model-Based Optimization method to achieve automatic hyper -parameter optimization. Six variables having causal relationships with shear stiffness were extracted via mechanism and model analysis, including the effect of weld collar that cannot be considered in existing models and subsequently constituting a database of 425 push-out tests. Then the ATDF model was trained by combining the advantages of deep learning, ensemble learning, and auto-tuning techniques. It was approved to significantly outperform representative benchmark models with R values of 0.91 and 0.87 for training and testing sets. The ATDF was subjected to attribute importance analysis, which quantified the stud diameter and concrete elastic modulus as the most significant variables for shear stiffness, with the stud elastic modulus having the minimal effect. The model uncertainty of ATDF was further evaluated, revealing that it had the lowest bias and variability than those in existing empirical or semi-empirical models. Finally, the reliability analysis was conducted and the partial factors of ATDF under specified target reliability were derived.

2022