O propósito desta dissertação é apresentar o uso da opinião de especialistas e outras questões relevantes acerca do assunto na avaliação das incertezas em estudos de análise de risco e confiabilidade, com apresentação de um estudo de caso prático. Em estudos de confiabilidade umas das principais preocupações está na determinação das frequências de ocorrência dos eventos e seu comportamento ao longo do tempo. Muitas vezes, os dados de frequência estão obsoletos, não estão disponíveis ou mesmo, não são suficientes para se avaliar a probabilidade de ocorrência de eventos. Nestes casos, a elicitação da opinião de especialista surge como uma alternativa a suplementar estas ausências de dados possibilitando assim uma melhor análise das incertezas. Baseado na condição da subjetividade, a elicitação dos especialistas tem como objetivo quantificar as incertezas a partir da experiência prévia e estado atual de conhecimento. Combinado com métodos matemáticos, a elicitação possibilita o gerenciamento de conflitos de informações de forma a atingir o consenso e possibilitar uma análise subjetiva dos problemas. / The purpose of this dissertationis to present the use of expert opinion and other relevant issues on the subjective assessment of uncertainties in risk analysis and reliability studies, presenting a practical case study. In reliability studies a major concern is to determine the frequencies of occurrence of events and their behavior through time. Often, the available data are not representative enough to evaluate the event probability or it is obsolete for use. In these cases, the elicitation of expert opinion is an alternative to supplement these data absences, Thus enabling a better uncertainties analysis. Based on the subjectivity condition, the elicitation of experts aims to quantify the uncertainty considering the previous experiences and current state of knowledge. Combined with mathematical elicitation methods, it enables the manegement of information conflicts in order to reach consensus and makes possible a subjective analysis of problems.

This study had three purposes: (1) to identify differential item functioning (DIF) on the PPVT-III (Forms A & B) using a partial correlation method, (2) to find a consistent pattern in items identified as underestimating ability in each ethnic minority group, and (3) to compare findings from an expert judgment method and a partial correlation method. Hispanic, African American, and white subjects for the study were provided by American Guidance Service (AGS) from the standardization sample of the PPVT-III; English language learners (ELL) of Mexican descent were recruited from school districts in Central and South Texas. Content raters were all self-selected volunteers, each had advanced degrees, a career in education, and no special expertise of ELL or ethnic minorities. Two groups of teachers participated as judges for this study. The "expert" group was selected because of their special knowledge of ELL students of Mexican descent. The control group was all regular education teachers with limited exposure to ELL. Using the partial correlation method, DIF was detected within each group comparison. In all cases except with the ELL on form A of the PPVT-III, there were no significant differences in numbers of items found to have significant positive correlations versus significant negative correlations. On form A, the ELL group comparison indicated more items with negative correlation than positive correlation [χ2 (1) = 5.538; p=.019]. Among the items flagged as underestimating ability of the ELL group, no consistent trend could be detected. Also, it was found that none of the expert judges could adequately predict those items that would underestimate ability for the ELL group, despite expertise. Discussion includes possible consequences of item placement and recommendations regarding further research and use of the PPVT-III.

This study had three purposes: (1) to identify differential item functioning (DIF) on the PPVT-III (Forms A & B) using a partial correlation method, (2) to find a consistent pattern in items identified as underestimating ability in each ethnic minority group, and (3) to compare findings from an expert judgment method and a partial correlation method. Hispanic, African American, and white subjects for the study were provided by American Guidance Service (AGS) from the standardization sample of the PPVT-III; English language learners (ELL) of Mexican descent were recruited from school districts in Central and South Texas. Content raters were all self-selected volunteers, each had advanced degrees, a career in education, and no special expertise of ELL or ethnic minorities. Two groups of teachers participated as judges for this study. The "expert" group was selected because of their special knowledge of ELL students of Mexican descent. The control group was all regular education teachers with limited exposure to ELL. Using the partial correlation method, DIF was detected within each group comparison. In all cases except with the ELL on form A of the PPVT-III, there were no significant differences in numbers of items found to have significant positive correlations versus significant negative correlations. On form A, the ELL group comparison indicated more items with negative correlation than positive correlation [χ2 (1) = 5.538; p=.019]. Among the items flagged as underestimating ability of the ELL group, no consistent trend could be detected. Also, it was found that none of the expert judges could adequately predict those items that would underestimate ability for the ELL group, despite expertise. Discussion includes possible consequences of item placement and recommendations regarding further research and use of the PPVT-III.

Many workers are daily exposed to chemical risks in their work place that has to be assessed and controlled. Due to exposure variability, repeated and random measurements should be conducted for valid estimates of the average exposure. Traditionally, experts such as safety engineers, work environment inspectors, and occupational hygienists, have performed the measurements. In self assessment of exposure (SAE), the workers perform unsupervised exposure measurements of chemical agents. This thesis studies a prerequisite for SAE, i.e. the workers’ mental models of chemical exposure. Further, the workers’ mental models are contrasted with experts’ reasons and decision criteria for measurement. Both qualitative and quantitative data generated from three studies (Paper I, II, and III) were used to describe the workers’ mental model of chemical exposure. SAE was introduced to workers in three different industries; transports (benzene), sawmill industry (monoterpenes), and reinforced plastic industry (styrene). By interviews, qualitative data were collected on the workers’ interpretation of measurement results and preventive actions. To evaluate the validity of worker measurement, the measurements were compared with expert measurements. The association between each worker’s number of performed measurement and mean level and variability in exposure concentrations was calculated. Mean absolute percent/forecast error (MAPE) was used to assess whether the workers’ decision models were in accordance with a coherence or correspondence model. In Paper IV, experts (safety engineers, work environment inspectors, and occupational hygienists) were interviewed to elucidate their mental models about the triggers and decision criteria for exposure measurements. The results indicate that the workers’ measurement results were in agreement with experts’. However, the measurement results were not a strong enough signal to induce workers to take preventive actions and sustained exposure measurements even if the measurement result were close to the occupational exposure limit. The fit was best for the median model, indicating that the workers’ mental models for interpretation of measurement data can best be described by the coherence theory rather than by the correspondence theory. The workers seemed to mentally reduce the variation in the exposure to a measure of central tendency (the median), and underestimated the average exposure level. The experts were found to directly take preventive actions instead of performing exposure measurements. When they performed exposure measurements, a worst case sampling strategy was most common. An important trigger for measurement for the experts was “request from the employer” (safety engineers), “legal demands” (work environment inspectors), and “symptoms among workers” (occupational hygienists). When there was a trigger, all experts mentioned expectations of high exposure level as a decision criterion for measurements. In conclusion, the studies suggest that workers’ mental interpretation model is best described in terms of a coherence model rather than a model of correspondence. The workers reduced the variation mentally in favor of an estimate of average exposure (median), which may imply that they underestimate short-term, high exposure health risks. A consequence is that interpretation of measurements such as SAE cannot be given to the individual worker without some support, e.g. from an expert. However, experts often chose to directly take preventive actions, without measuring the exposure. The results indicate that also the experts need support e.g. from the legal system if exposure measurements are to be done.

O propósito desta dissertação é apresentar o uso da opinião de especialistas e outras questões relevantes acerca do assunto na avaliação das incertezas em estudos de análise de risco e confiabilidade, com apresentação de um estudo de caso prático. Em estudos de confiabilidade umas das principais preocupações está na determinação das frequências de ocorrência dos eventos e seu comportamento ao longo do tempo. Muitas vezes, os dados de frequência estão obsoletos, não estão disponíveis ou mesmo, não são suficientes para se avaliar a probabilidade de ocorrência de eventos. Nestes casos, a elicitação da opinião de especialista surge como uma alternativa a suplementar estas ausências de dados possibilitando assim uma melhor análise das incertezas. Baseado na condição da subjetividade, a elicitação dos especialistas tem como objetivo quantificar as incertezas a partir da experiência prévia e estado atual de conhecimento. Combinado com métodos matemáticos, a elicitação possibilita o gerenciamento de conflitos de informações de forma a atingir o consenso e possibilitar uma análise subjetiva dos problemas. / The purpose of this dissertationis to present the use of expert opinion and other relevant issues on the subjective assessment of uncertainties in risk analysis and reliability studies, presenting a practical case study. In reliability studies a major concern is to determine the frequencies of occurrence of events and their behavior through time. Often, the available data are not representative enough to evaluate the event probability or it is obsolete for use. In these cases, the elicitation of expert opinion is an alternative to supplement these data absences, Thus enabling a better uncertainties analysis. Based on the subjectivity condition, the elicitation of experts aims to quantify the uncertainty considering the previous experiences and current state of knowledge. Combined with mathematical elicitation methods, it enables the manegement of information conflicts in order to reach consensus and makes possible a subjective analysis of problems.

Les digues de protection contre les inondations sont d’une importance stratégique incontournable pour la sécurité des personnes et des biens. Une meilleure connaissance de leur fiabilité structurelle constitue un enjeu majeur pour les ingénieurs et pour les gestionnaires de ces ouvrages afin de répondre aux réglementations en vigueur et potentiellement les faire évoluer. La réglementation en France relative à la sûreté des ouvrages hydrauliques exige la réalisation d’études de dangers, au sein desquelles les démarches probabilistes d’évaluation de la sécurité prennent une place de plus en plus importante. De par la complexité de leurs mécanismes de rupture et l’absence de condition d’état-limite précis pour certains mécanismes de défaillance tels que l’érosion interne, la surverse ou l’affouillement, le calcul d’une probabilité de défaillance par des approches quantitatives demeure à ce jour impossible. Les digues induisent des problématiques particulières pour l’évaluation de leur fiabilité structurelle où l’intervention d’experts s’avère nécessaire et centrale. Ceux-ci doivent procéder à l’interprétation des données disponibles et la prise en compte de leurs incertitudes, pour pouvoir ensuite évaluer la fiabilité structurelle de digues en termes de probabilité de défaillance. L’objectif de la thèse est l’élaboration d’une démarche complète d’aide à l’évaluation probabiliste de la fiabilité structurelle des digues à partir du jugement expert. Une démarche scientifiquement justifiée pour le recueil et l’exploitation des évaluations expertes, incertaines mais quantitatives, de la fiabilité structurelle des ouvrages, sous la forme d’une probabilité de défaillance ou d’un coefficient de sécurité, assorti(e) d’une marge d’incertitude probabiliste. Afin de répondre à cet objectif, deux démarches ont été développée, « EiCAD » et « EiDA », toutes reposant (dans des ordres différents) sur les phases suivantes :- Une phase d’élicitation individuelle des avis experts (Ei) permettant le recueil des évaluations expertes probabilistes par la construction d’un formulaire de questionnement ;- Une phase de calibration (C) permettant de pondérer les évaluations expertes en fonction des degrés de précision et de justesse ;- Une phase d’agrégation (A) permettant une prise en compte simultanée de plusieurs évaluations expertes probabilistes ;- Une phase de débiaisage (D) permettant de traiter les biais susceptibles d’entacher les évaluations expertes probabilistes. Les démarches développées ont été mises en œuvre sur des cas de digues du Drac, dans l’agglomération grenobloise, pour évaluer la probabilité de défaillance, par jugement expert, vis-à-vis de mécanisme de rupture par glissement et par érosion interne / River levees as protective measures against flooding are a matter of utmost strategic importance for the security of people and property. A better knowledge of their structural reliability is a major challenge for engineers and managers of these structures in order to meet current regulations and potentially develop them. In France, the regulations relating to the safety of hydraulic structures require the realization of hazard studies, in which probabilistic safety evaluation procedures take on a more and more important role. Due to the complexity of their failure mechanisms and the lack of a specific condition of limit-state for some failure mechanisms such as internal erosion and overtopping or scour, calculating a probability of failure by quantitative approaches remains impossible to this day. Levees induce specific problems in evaluating their structural reliability where expert intervention is necessary and pivotal. They must interpret the available data and take into account the uncertainties in their analysis, in order to evaluate the structural reliability of levees in terms of probability of failure. The aim of the thesis is to develop and elaborate a complete approach for supporting probabilistic evaluation of structural reliability of levees based on expert judgments. It is designed as a scientifically justified approach to collect and use uncertain but quantitative expert evaluations of structural reliability, in the form of a failure probability or a safety factor, accompanied by a margin of probabilistic uncertainty. To meet this goal, two approaches have been developed, "EiCAD" and "EiDA" composed of the following phases (in different orders):- individual elicitation phase of expert judgment (Ei) allowing the collection of probabilistic expert evaluations by a constricted questionnaire ;- calibration phase (C) to weigh the probabilistic expert evaluations elicited depending on the degrees of precision and accuracy that can be provided;- aggregation phase (A) during which the probabilistic expert evaluations elicited by several experts are taken into account ;- debiasing phase (D) during which biases that may affect the probabilistic expert evaluations are removed. The developed approaches have been implemented for the cases of Drac levees, located in the Grenoble agglomeration, to assess the probability of failure, by expert judgment, with regard to sliding and internal erosion mechanism of failure

The evaluation methods of competitors in figure skating are the key problem of this sport. The 6.0 system of evaluation was in use until the year 2004. In such system referee compares competitors one by one and decides on the rank. The 6.0 system can be described by method of Expert Judgment and/or Group Participation. In year 2004 International Skating Union introduced the new system. In this new system is in the role of the decision maker mainly the competitor not the referee. The competitor chooses elements of his program which maximized the total point benefit. We can find out the point value of every element in SOV -- Scale of Values. Nowadays the skater can decide according to the Decision Making under Multiple Criteria theory, we use Weighted Sum Approach method which is sufficient for our purpose. In this thesis both systems are going to be explained on particular cases and linked with methods of decision making theory.

Cette thèse explore l’utilisation des réseaux Bayésiens (RB) afin de répondre à des problématiques de dégradation en grandes dimensions concernant des infrastructures du génie civil. Alors que les approches traditionnelles basées l’évolution physique déterministe de détérioration sont déficientes pour des problèmes à grande échelle, les gestionnaires d’ouvrages ont développé une connaissance de modèles nécessitant la gestion de l’incertain. L’utilisation de la dépendance probabiliste se révèle être une approche adéquate dans ce contexte tandis que la possibilité de modéliser l’incertain est une composante attrayante. Le concept de dépendance au sein des RB s’exprime principalement de deux façons. D’une part, les probabilités conditionnelles classiques s’appuyant le théorème de Bayes et d’autre part, une classe de RB faisant l’usage de copules et corrélation de rang comme mesures de dépendance. Nous présentons à la fois des contributions théoriques et pratiques dans le cadre de ces deux classes de RB ; les RB dynamiques discrets et les RB non paramétriques, respectivement. Des problématiques concernant la paramétrisation de chacune des classes sont également abordées. Dans un contexte théorique, nous montrons que les RBNP permet de caractériser n’importe quel processus de Markov. / This thesis explores high-dimensional deterioration-related problems using Bayesian networks (BN). Asset managers become more and more familiar on how to reason with uncertainty as traditional physics-based models fail to fully encompass the dynamics of large-scale degradation issues. Probabilistic dependence is able to achieve this while the ability to incorporate randomness is enticing.In fact, dependence in BN is mainly expressed in two ways. On the one hand, classic conditional probabilities that lean on thewell-known Bayes rule and, on the other hand, a more recent classof BN featuring copulae and rank correlation as dependence metrics. Both theoretical and practical contributions are presented for the two classes of BN referred to as discrete dynamic andnon-parametric BN, respectively. Issues related to the parametrization for each class of BN are addressed. For the discrete dynamic class, we extend the current framework by incorporating an additional dimension. We observed that this dimension allows to have more control on the deterioration mechanism through the main endogenous governing variables impacting it. For the non-parametric class, we demonstrate its remarkable capacity to handle a high-dimension crack growth issue for a steel bridge. We further show that this type of BN can characterize any Markov process.

The general purpose of this thesis is to contribute to further understanding of the academic appointment process explored and defined as participation in a collegial educational process. The appointment process for academic positions has historically been regulated by state authorities ever since the first university was established in Sweden and has continuously been questioned for necessity, procedure etc. The object of study is the appointment process focusing the consideration of teaching skill in appointing academic teachers. A theoretical construction is used as a method in order to grasp what the experts and applicants consider. The thesis draws theoretical inspiration from the French sociologist Pierre Bourdieu especially his work on social practice and his explanations within praxeological knowledge. In this thesis cultural capital, habitus and doxa are used as concepts for constructing a social practice. Inspired by Bourdieu’s concepts, the appointment process is made visible grounded on documentation: judgments of qualifications written by external experts and the applicants’ documentation in their applications. The empirical material on merits is analyzed according to Bourdieu’s indicators on symbolic capacities. The disposition of habitus (as an inner organizing principle) is limited to cultural capital and background demographic data. The indicators on scientific skill are also transmitted into symbolic capacities on teaching skill. Three appointments as assistant professors are analyzed, framed by information on advertisement, description of documentation, time lapse and final decision in appointment committees. The main conclusions are that the experts select whom to appoint using their practical sense unaware of the driving forces, explained as social practice. The experts act in line with the purpose of the assignment and they follow all the rules and instructions. Teaching skill is focused by the applicants and experts as practical mastery in the subject field (pedagogical authority). Selection is explained by the concept of habitus. Another conclusion is the tendency to “nuanced” co-optation similar to when appointments were made by self selection and teaching ability was important in early 19th century. A final conclusion is that in positioning of arguments in shared beliefs (doxa) in questioning the appointment process, researchers in the early years of this century represent heterodox opinions.