In this thesis an optimal stopping problem related to the classical secretary problem is studied. The theory of optimal stopping represents a special branch of stochastic optimization. Here the socalled full information best choice problem with a known number of offers is generalized by maximizing the probability of selecting an r-candidate, where an offer is called r-candidate if it is not lower than the maximal offer reduced by function r. In the first part discrete time is investigated. For this optimal stopping problem to select an r-candidate an optimal stopping time is indicated, the suboptimal myopic stopping time is displayed and threshold rules are studied including asymptotic behaviour. The basis of this optimal stopping problem is displayed in a general setting where the payoff depends on the prophet´s choiceand on the maximal offer, i.e. the value of the prophet. As a further application the mean of the ratio of the gambler´s choice and prophet´s value is investigated. Then in the second part offers arrive in continuous time. Offers are presented according to random arrival times and the horizon terminating the period of choosing is taken to be fixed and random. Here stress is layed on the geometric and on the exponential distribution, i.e. the Poisson process. In the final part the optimal stopping problem of maximizing the duration of owning a sufficiently good offer is applied to the concept of an r-candidate. A distinction between an overall and a temporary r-candidate is made. The duration of owning an r-candidate is investigated for a finite number of offers with regard to recall. The duration problem with discounted epochs is resolved. Finally the duration of owning an r-candidate is considered regarding the Poisson process where the horizon is fixed and exponentially distributed.

Dans cette thèse, nous étudions des stratégies d’allocation séquentielle de ressources. Le modèle statistique adopté dans ce cadre est celui du bandit stochastique à plusieurs bras. Dans ce modèle, lorsqu’un agent tire un bras du bandit, il reçoit pour récompense une réalisation d’une distribution de probabilité associée au bras. Nous nous intéressons à deux problèmes de bandit différents : la maximisation de la somme des récompenses et l’identification des meilleurs bras (où l’agent cherche à identifier le ou les bras conduisant à la meilleure récompense moyenne, sans subir de perte lorsqu’il tire un «mauvais» bras). Nous nous attachons à proposer pour ces deux objectifs des stratégies de tirage des bras, aussi appelées algorithmes de bandit, que l’on peut qualifier d’optimales. La maximisation des récompenses est équivalente à la minimisation d’une quantité appelée regret. Grâce à une borne inférieure asymptotique sur le regret d’une stratégie uniformément efficace établie par Lai et Robbins, on peut définir la notion d’algorithme asymptotiquement optimal comme un algorithme dont le regret atteint cette borne inférieure. Dans cette thèse, nous proposons pour deux algorithmes d’inspiration bayésienne, Bayes-UCB et Thompson Sampling, une analyse à temps fini dans le cadre des modèles de bandit à récompenses binaires, c’est-à-dire une majoration non asymptotique de leur regret. Cette majoration permetd’établir l’optimalité asymptotique des deux algorithmes. Dans le cadre de l’identification des meilleurs bras, on peut chercher à déterminer le nombre total d’échantillons des bras nécessaires pour identifier, avec forte probabilité, le ou les meilleurs bras, sans la contrainte de maximiser la somme des observations. Nous définissons deux termes de complexité pour l’identification des meilleurs bras dans deux cadres considérés dans la littérature, qui correspondent à un budget fixé ou à un niveau de confiance fixé. Nous proposons de nouvelles bornes inférieures sur ces complexités, et nous analysons de nouveaux algorithmes, dont certains atteignent les bornes inférieures dans des cas particuliers de modèles de bandit à deux bras, et peuvent donc être qualifiés d’optimaux. / In this thesis, we study strategies for sequential resource allocation, under the so-called stochastic multi-armed bandit model. In this model, when an agent draws an arm, he receives as a reward a realization from a probability distribution associated to the arm. In this document, we consider two different bandit problems. In the reward maximization objective, the agent aims at maximizing the sum of rewards obtained during his interaction with the bandit, whereas in the best arm identification objective, his goal is to find the set of m best arms (i.e. arms with highest mean reward), without suffering a loss when drawing ‘bad’ arms. For these two objectives, we propose strategies, also called bandit algorithms, that are optimal (or close to optimal), in a sense precised below. Maximizing the sum of rewards is equivalent to minimizing a quantity called regret. Thanks to an asymptotic lower bound on the regret of any uniformly efficient algorithm given by Lai and Robbins, one can define asymptotically optimal algorithms as algorithms whose regret reaches this lower bound. In this thesis, we propose, for two Bayesian algorithms, Bayes-UCB and Thompson Sampling, a finite-time analysis, that is a non-asymptotic upper bound on their regret, in the particular case of bandits with binary rewards. This upper bound allows to establish the asymptotic optimality of both algorithms. In the best arm identification framework, a possible goal is to determine the number of samples of the armsneeded to identify, with high probability, the set of m best arms. We define a notion of complexity for best arm identification in two different settings considered in the literature: the fixed-budget and fixed-confidence settings. We provide new lower bounds on these complexity terms and we analyse new algorithms, some of which reach the lower bound in particular cases of two-armed bandit models and are therefore optimal

Problemområdet för den här uppsatsen var styrning och jämförelser. Syftet var att analysera och jämföra vilken skola som synliggjordes i den kommunala styrningen i fyra kommuner; Danderyd, Piteå, Täby och Vellinge. Den teoretiska basen utgjordes av Focuaults governmentalitybegrepp, och den – framför allt internationella – forskningen om dataproduktion och jämförelser på en mellanstatlig nivå. Gemensamt för den presenterade forskningen i uppsatsen är att produktionen av data och jämförelser ligger till grund för en informell styrning som inte är vetenskapligt förankrad. Analysen av kommunerna gjordes utifrån de tre begreppen governing by numbers (dataproduktion), governance by comparison (jämförelser) och best practice (det goda exemplet). Resultaten visade att de granskade kommunerna till mycket stor del styrde med hjälp av dataproduktion, det vill säga att det sker en kvantifiering av verksamheten. I många fall utsattes även den dataproduktionen för jämförelser med andra kommuner och/eller med riket. Produktionen av data var så pass omfattande i dessa kommuner att det föreföll som att endast det som kan mätas togs upp i verksamhetsplaneringen. Mätbar verksamhet lyftes upp framför verksamhet med mjukare värden, vilket bland annat innebar att professionen i stort sett var osynliggjord. Resultaten visade också att uppföljning och utvärdering inte har något genomslag i verksamhetsstyrningsdokumenten.

The ability to sustain small businesses operating in war-torn areas is important not only to the business owners, but also to foreign communities receiving United States contract services for recovery from widespread decimation. While all small businesses address a wide range of issues, businesses operating in war-torn areas also face cultural diversity, local regulations, and potential threats to employee safety. The conceptual framework for this exploratory multiple case study was transformational-transactional leadership theory, guiding the research to discover traits and strategies of successful leaders in the population of small businesses that were profitable beyond 5 years while operating in the war-torn area of Afghanistan. In addition to participant questionnaires and review of the businesses' balance sheets, income statements, and tax returns, data were collected from 3 CEO participants in face-to-face, semistructured interviews. Participants' verbatim comments were analyzed via thematic analysis. The coding system evolved from applying preliminary codes to a small sample of data and reiteratively refining the codes as prominent themes emerged. Participants identified unique challenges of working with a multinational workforce. There were 3 primary findings: successful leaders used elements of both transformational and transactional leadership; the most important strategy was gaining knowledge of regional infrastructure and customs; and successful leaders used management assistance. These findings may contribute to social change by prompting small business leaders to re-examine their perspectives on workforce diversity; they will also enable leaders who provide services overseas to realize profitable business goals while contributing to foreign local economies.

The local district in this study has not made adequate yearly progress in the past several years in language arts literacy on state assessments. Particularly problematic were poor reading skills among district students. Poor literacy skills negatively affect student learning across the curriculum. The purpose of this case study was to identify teachers' and administrators' perceptions of best literacy practices, professional development, and administrative decisions regarding literacy learning for primary students in reading at a strong performing elementary school in the district. The target school was selected to help address reading failure for the low-performing schools in this district. Bloom's taxonomy of learning, which indicates that higher-level learning is based on foundational knowledge that is often provided at the primary level, was the framework for this study. A bounded case study was conducted that included a purposeful sample of 7 elementary teachers of language arts from Pre-K to 2nd grades and 2 administrators at the target elementary school. Classroom observations and interviews were used to collect data. NVivo was used to assist in coding, analysis of data, and identification of recurring themes. The findings indicated that an outcome-based curriculum incorporating Bloom's levels of learning coupled with supportive district decisions regarding literacy were key components driving literacy success at the target school. The findings were incorporated into a policy paper as a project to propose and support elementary level reading curriculum changes and administrative decisions regarding literacy success for elementary students in the local district. Implications for positive social change might be far reaching as elementary school students in this district benefit from literacy skills that improve their academic success and ultimately their overall quality of life.

Compulsory care of a child is one of the most intrusive interventions that can be made in a child's life, but a protective task that social services have been obliged to carry out. In the case of compulsory care of a child, the social secretary is faced with a number of different difficulties and dilemmas that can be linked to coercion in LVU legislation and consideration of the child's best interests. The aim of this qualitative study is to investigate social workers, in social services' child and family investigation, experience of how the child's best interests are taken into account in LVU processes och what thoughts and ethical dilemmas arise for social workers in connection to the LVU process in the meetings with children and parents, and also how can this be understood in relation to their professional role. By using an interview based qualitative method, this study strives to reach a deeper understanding of social workers' experience of the subject matter. The results of this study shows that the experience of the child's best interests is a concept that social workers must constantly define and describe as situational, based on the child's situation. A common description of the child's best interests is that it is a concept that needs a definition and frame of reference, as the lack of a definition makes it more difficult for social workers to consider what is in the child's best interests. This study reaches the conclusion that social workers experience the LVU process to be harmful to the relationship between both children and parents, and parents and social services. Based on this, the social workers felt that it was a huge ethical dilemma to use LVU, as the implementation of the LVU law was both emotionally stressful and comes with its limitations. This despite knowing that LVU should function as a protection for the child and its best interests.

This essay takes aim on the issue that the concept of the best interest of the child has no distinct legal definition. This essay means to explore how the concept is constructed by the social workers in investigations about custody, accommodation and contact. Furthermore, previous research suggests that social norms have an influence on the construction of the concept. Therefore, this essay also aims to understand if this is the case and to what extent norms have an influence on the construction of the best interest of the child. Finally, the goal is also to understand how legal certainty is affected by the influence of social norms. This essay uses a content analysis of investigations that are presented in the court’s legal documents. The content analysis uses the theoretical framework from Håkan Hydéns norm model. The results show that social workers mainly use circumstances in the individual case to create meaning of what is and what is not the best interest of the child. Social workers also use their own knowledge and experience, as well as scientific knowledge. Lastly, social workers sometimes use their own interpretations, opinions and values to give meaning to what the best interest of the child means. The results also show that there is room for norms to influence the assessment of what is in the best interest of the child, but at the same time the result can’t explain to what extent social norms have an influence. Furthermore, the results show that the influence of norms may affect the legal certainty of children negatively.

No description available.

Within the Brazilian strategy to reform out-of-home care services, efforts have been directed to the prioritization of foster care over congregate care. This study draws from the perspective that childhood is socially construed, therefore child protection systems are dependent of notions and ideals of childhood, especially concerning the child deprived of parental care. Interviews with ten professionals involved in the implementation and execution of foster care services in different cities were conducted for this study. Thematic analysis of interviews was triangulated with the contents of National Guidelines for out-of-home care services and legal provisions with the aim of investigating how ideas on children deprived of parental care and their best interests are translated into practice. Three research questions guided the study: (1) how participants perceive the out-of-home care reform and the provisions of rights in different care modalities, especially regarding how children placed in different types of out-of-home care are perceived, (2) how participants view children’s best interests and which practices are believed to secure them and (3) how practitioners’ views relate to the contents of the National Guidelines. Five themes emerged in the analysis: a scientific and legal defense of (1) foster care as the most up to date form of out-of-home care, the prioritization of (2) children’s needs for individualized parental care, that (3) practitioners’ strong discretion is conditioned by foster families’ choices, that (4) institutionalization and group are detrimental to children, and the invocation that (5) children must be onboard. The study concludes that a clearer conceptualization of the rights and bests interests of children deprived of parental is required to better inform the reform of child protection and its practices, where consideration to children’s participation could be extended over acceptance to decisions.

No description available.