Empty answers are a major problem by processing pattern matching queries in graph databases. Especially, there can be multiple reasons why a query failed. To support users in such situations, differential queries can be used that deliver missing parts of a graph query. Multiple heuristics are proposed for differential queries, which reduce the search space. Although they are successful in increasing the performance, they can discard query subgraphs relevant to a user. To address this issue, the authors extend the concept of differential queries and introduce top-k differential queries that calculate the ranking based on users’ preferences and significantly support the users’ understanding of query database management systems. A user assigns relevance weights to elements of a graph query that steer the search and are used for the ranking. In this paper the authors propose different strategies for selection of relevance weights and their propagation. As a result, the search is modelled along the most relevant paths. The authors evaluate their solution and both strategies on the DBpedia data graph.

Opsomming Daar bestaan 'n behoefte aan 'n objektiewe maatstaf om die gehalte van akademiese publikasies te bepaal en te vergelyk. Hierdie navorsing het die invloed of reaksie wat deur 'n publikasie gegenereer is uit verwysingsdata bepaal. Daar is van 'n iteratiewe algoritme gebruik gemaak wat gewigte aan verwysings toeken. In die Internetomgewing word hierdie benadering reeds met groot sukses toegepas deur onder andere die PageRank-algoritme van die Google soekenjin. Hierdie en ander algoritmes in die Internetomgewing is bestudeer om 'n algoritme vir akademiese artikels te ontwerp. Daar is op 'n variasie van die PageRank-algoritme besluit wat 'n Invloedwaarde bepaal. Die algoritme is op gevallestudies getoets. Die empiriese studie dui daarop dat hierdie variasie spesialisnavorsers se intu¨ıtiewe gevoel beter weergee as net die blote tel van verwysings. Abstract Ranking of journals are often used as an indicator of quality, and is extensively used as a mechanism for determining promotion and funding. This research studied ways of extracting the impact, or influence, of a journal from citation data, using an iterative process that allocates a weight to the source of a citation. After evaluating and discussing the characteristics that influence quality and importance of research with specialist researchers, a measure called the Influence factor was introduced, emulating the PageRankalgorithm used by Google to rank web pages. The Influence factor can be seen as a measure of the reaction that was generated by a publication, based on the number of scientists who read and cited itA good correlation between the rankings produced by the Influence factor and that given by specialist researchers were found. / Mathematical Sciences / M.Sc. (Operasionele Navorsing)

Bakgrund: Leverantörer har en allt viktigare roll för verksamheter. Med en strävan om att kunna minska lagernivåer krävs det en kontinuerlig påfyllning av lager. För att kunna uppnå det behöver leverantörerna vara flexibla och kunna möta ändringar på kort sikt. Företag vill även försäkra sig om att leverantören kan förse deras behov även i framtiden. Detta gör att företag vill skapa sig en förståelse av hur väl leverantörerna presterar och kunna vidta åtgärder för att förebygga problem, något som kan göras genom prestationsmätning av leverantörer. Syfte: Syftet med studien är att kartlägga Carlsberg Sverige´s process för prestationsmätning av sina leverantörer samt finna brister som påverkar processen. Studien syftar även till att rangordna Carlsberg Sverige’s leverantörers prestationer. Slutligen ska studien ge förbättringsförslag till prestationsmätningsprocessen utifrån funna brister samt undersöka vad Carlsberg Sverige’s kan göra för att vidare utveckla rangordningen av leverantörer. Metod: Studien har genomförts via ostrukturerade intervjuer, semi-strukturerade intervjuer, observationer samt insamling av data från affärssystemet SAP och Supplier Performance. I början av studien genomfördes en processkartläggningen för att identifiera brister som påverkar processen för prestationsmätning av leverantörer. Vidare gjordes en rangordning av Carlsberg Sverige´s leverantörer utifrån deras prestationer. Slutligen presenteras en åtgärdsplan för hur Carlsberg Sverige ska kunna gå vidare med bristerna samt att vidare utveckla rangordningen för deras leverantörer. Slutsats: Författarna av studien har identifierat brister som påverkar Carlsberg Sverige´s process för prestationsmätning av leverantörer och givit förslag på åtgärdsplaner hur man ska gå tillväga för att komma till bukt med bristerna. Brister som 4 identifierats är bland annat att företaget har ett svårhanterligt verktyg för prestationsmätning av leverantörer samt att det saknas incitament att rapportera i verktyget. Det har även funnits brister i arbete med prognoser, produktionsplanering och operativt inköp som påverkar prestationsmätningen. Därefter har också en rangordning av företagets tio viktigaste leverantörer av förpackningsmaterial samt rangordning för de tio viktigaste råvaruleverantörer genomförts. Det har även givits förslag på hur rangordningen av leverantörer kan förbättras i framtiden. / Background: Suppliers nowadays play a large part for producing companies. These companies strive for less inventory and therefore there is a need for continuous replenishment of stocks. To achieve this, the suppliers need to be flexible and able to meet changes in short time demand. Companies also want to ensure that the suppliers can meet their demand of material in the future. It is therefore of great interest for the companies to understand how well the suppliers are performing, which can be done using performance measurements. Purpose: The purpose of this study is to map out Carlsberg Sverige’s process for performance measurement of their suppliers and identify problems affecting the process. The study also aims to find a way to rank Carlsberg Sverige’s suppliers. Finally, the identified problems in the process will be given suggestions of improvements. Likewise, the way of ranking will be given suggestions of improvements. Method: The data for this study has been collected using unstructured interviews. semistructured interviews, but also through observations and data from SAP and Carlsberg Sverige’s developed tool for performance measurement. To identify problems in the process, mapping out the process was essential. After that a ranking was made of the suppliers’ performances. Lastly the suggestions for improvement of the process and the ranking was made. Conclusion: The authors of this study has identified problems in Carlsberg Sverige’s process of performance measurements of suppliers and have created plans for improvement. The problems of the process is for instance that the tool for performance measurements of suppliers is not user friendly and that the users of the tool lack 6 incentives to report deviations. There has also been identified problems in forecasting, production planning and operative purchasing that are affecting the process. Carlsberg Sverige’s ten most important suppliers of packaging materials as well as the ten most important suppliers of raw materials have been ranked depening on their performances. The study also gives suggestions of further developement of the ranking.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Citation analysis is an important tool in the academic community. It can aid universities, funding bodies, and individual researchers to evaluate scientific work and direct resources appropriately. With the rapid growth of the scientific enterprise and the increase of online libraries that include citation analysis tools, the need for a systematic evaluation of these tools becomes more important. The research presented in this study deals with scientific research output, i.e., articles and citations, and how they can be used in bibliometrics to measure academic success. More specifically, this research analyses algorithms that rank academic entities such as articles, authors and journals to address the question of how well these algorithms can identify important and high-impact entities. A consistent mathematical formulation is developed on the basis of a categorisation of bibliometric measures such as the h-index, the Impact Factor for journals, and ranking algorithms based on Google’s PageRank. Furthermore, the theoretical properties of each algorithm are laid out. The ranking algorithms and bibliometric methods are computed on the Microsoft Academic Search citation database which contains 40 million papers and over 260 million citations that span across multiple academic disciplines. We evaluate the ranking algorithms by using a large test data set of papers and authors that won renowned prizes at numerous Computer Science conferences. The results show that using citation counts is, in general, the best ranking metric. However, for certain tasks, such as ranking important papers or identifying high-impact authors, algorithms based on PageRank perform better. As a secondary outcome of this research, publication trends across academic disciplines are analysed to show changes in publication behaviour over time and differences in publication patterns between disciplines. / AFRIKAANSE OPSOMMING: Sitasiesanalise is ’n belangrike instrument in die akademiese omgewing. Dit kan universiteite, befondsingsliggams en individuele navorsers help om wetenskaplike werk te evalueer en hulpbronne toepaslik toe te ken. Met die vinnige groei van wetenskaplike uitsette en die toename in aanlynbiblioteke wat sitasieanalise insluit, word die behoefte aan ’n sistematiese evaluering van hierdie gereedskap al hoe belangriker. Die navorsing in hierdie studie handel oor die uitsette van wetenskaplike navorsing, dit wil sê, artikels en sitasies, en hoe hulle gebruik kan word in bibliometriese studies om akademiese sukses te meet. Om meer spesifiek te wees, hierdie navorsing analiseer algoritmes wat akademiese entiteite soos artikels, outeers en journale gradeer. Dit wys hoe doeltreffend hierdie algoritmes belangrike en hoë-impak entiteite kan identifiseer. ’n Breedvoerige wiskundige formulering word ontwikkel uit ’n versameling van bibliometriese metodes soos byvoorbeeld die h-indeks, die Impak Faktor vir journaale en die rang-algoritmes gebaseer op Google se PageRank. Verder word die teoretiese eienskappe van elke algoritme uitgelê. Die rang-algoritmes en bibliometriese metodes gebruik die sitasiedatabasis van Microsoft Academic Search vir berekeninge. Dit bevat 40 miljoen artikels en meer as 260 miljoen sitasies, wat oor verskeie akademiese dissiplines strek. Ons gebruik ’n groot stel toetsdata van dokumente en outeers wat bekende pryse op talle rekenaarwetenskaplike konferensies gewen het om die rang-algoritmes te evalueer. Die resultate toon dat die gebruik van sitasietellings, in die algemeen, die beste rangmetode is. Vir sekere take, soos die gradeering van belangrike artikels, of die identifisering van hoë-impak outeers, presteer algoritmes wat op PageRank gebaseer is egter beter. ’n Sekondêre resultaat van hierdie navorsing is die ontleding van publikasie tendense in verskeie akademiese dissiplines om sodoende veranderinge in publikasie gedrag oor tyd aan te toon en ook die verskille in publikasie patrone uit verskillende dissiplines uit te wys.

Doctor of Philosophy / Department of Statistics / Paul Nelson / Panels of judges are often used to estimate consumer preferences for m items such as food products. Judges can either evaluate each item on several ordinal scales and indirectly produce an overall ranking, or directly report a ranking of the items. A complete ranking orders all the items from best to worst. A partial ranking, as we use the term, only reports rankings of the best q out of m items. Direct ranking, the subject of this report, does not require the widespread but questionable practice of treating ordinal measurement as though they were on ratio or interval scales. Here, we develop and study segmentation models in which the panel may consist of relatively homogeneous subgroups, the segments. Judges within a subgroup will tend to agree among themselves and differ from judges in the other subgroups. We develop and study the statistical analysis of mixture models where it is not known to which segment a judge belongs or in some cases how many segments there are. Viewing segment membership indicator variables as latent data, an E-M algorithm was used to find the maximum likelihood estimators of the parameters specifying a mixture of Mallow’s (1957) distance models for complete and partial rankings. A simulation study was conducted to evaluate the behavior of the E-M algorithm in terms of such issues as the fraction of data sets for which the algorithm fails to converge and the sensitivity of initial values to the convergence rate and the performance of the maximum likelihood estimators in terms of bias and mean square error, where applicable. A Bayesian approach was developed and credible set estimators was constructed. Simulation was used to evaluate the performance of these credible sets as confidence sets. A method for predicting segment membership from covariates measured on a judge was derived using a logistic model applied to a mixture of Mallows probability distance models. The effects of covariates on segment membership were assessed. Likelihood sets for parameters specifying mixtures of Mallows distance models were constructed and explored.

Seminario para optar al tìtulo de Ingeniero Comercial, Mención Economía / Este trabajo, inserto dentro de la literatura que revisa los incentivos de los alumnos frente a las notas, busca entregar evidencia de cómo entre el 2013 y el 2014 un grupo de alumnos buscó mejorar su puntaje PSU cambiándose a un colegio menos exigente donde tendrían una mejor bonificación a través del sistema ranking. Para esto realicé un análisis en base a estadística descriptiva, que permitiera encontrar diferencias producidas exclusivamente por la inclusión del ranking. Para lo anterior hice una comparación de lo que ocurrió con distintas variables como la tasa de cambio de colegio o los promedios generales para distintos grupos de alumnos divididos entre los que se relacionan con los mejores veinte colegios municipales y los que no. La principal limitación de este trabajo es que el efecto se vio principalmente entre 2013 y 2014, y no existen datos para 2015 aún, por lo que solo se puede ver un efecto significativo para un periodo. Un resultado más completo incluiría más periodos donde este efecto se produjo, pero para estoy hay que esperar más datos.

O Sistema Único de Saúde apresenta a descentralização da gestão das ações de saúde como uma das principais estratégias para a reorganização do setor. O poder municipal se apresenta como o principal responsável pela prestação da assistência da atenção à saúde, garantindo os princípios da universalidade e da integralidade do atendimento em todos os níveis da atenção. As Normas Operacionais Básicas e as Normas de Assistência à Saúde estabeleceram os mecanismos que impulsionaram o processo de descentralização das ações de saúde. O Estado do Ceará iniciou o processo de descentralização das ações de saúde para os municípios ao aderir ao Programa de Sistemas Unificados e Descentralizados de Saúde (SUDS). O estudo descreve este processo de descentralização, com ênfase na microrregião de Baturité, a partir da descentralização político-administrativa, da organização da regionalização e hierarquização como a identificação de mudanças no processo de atenção à saúde, a partir das ações de atenção à saúde da mulher, à saúde da criança, de controle de tuberculose e de controle de hipertensão O referencial do estudo foi a base normativa da Norma Operacional de Assistência à Saúde - 2001 (NOAS/ 2001). As condições oferecidas aos municípios para efetivar a descentralização das ações de saúde contribuíram para uma melhor estruturação dos serviços de saúde, resultado numa maior cobertura em ações básicas a partir da estratégia da Saúde da Família, e melhor organização da atenção em termos de hierarquização e regionalização como maior percentual de aplicação de recursos financeiros próprio. / The Brazilian Unified Health System presents the decentralization of management of health actions as one of the main strategies for reorganization of the sector. City Hall proves to be the main agent accountable for provision of health care support, guaranteeing the principles of universality and completeness of services at all levels of care. The Basic Operational Norms and Health Care Norms established the mechanisms which drove the process of decentralization of health actions. The state of Ceará began the process of decentralization of health actions to municipal administrations upon adhering to the Unified Health System (SUDS). This study describes this process of decentralization, with emphasis on the Baturité District, in terms of its political-administrative decentralization, organization of regionalization and ranking as identification of changes in the process of health care, based on health care services for women, children, tuberculosis control and control of high blood pressure. The benchmark for the study was the normative framework of the Health Care Operational Norms - NOAS/2001. The conditions offered to municipal administrations to perform decentralization of healthcare contributed to improvement in the Family Health structure, resulting in greater coverage in basic care from the standpoint of Family Health and better organization of care in terms of hierarchy and regionalization such as best percentage of investment of own financial resources.

Neste trabalho é estimado o valor do índice de mortes por quilômetro percorrido pela frota de veículos rodoviários no Brasil e em cada estado da federação nos anos de 2004 a 2008. Para determinar os valores da quilometragem anual média dos veículos - parâmetro necessário para estimativa do índice de mortes por veículo - quilômetro - desenvolveu-se um método apropriado tomando como referência a quantidade de combustível vendida pelas distribuidoras em cada estado. Os estados foram classificados em relação a todos os índices associados à mortalidade viária, assim como analisadas as relações entre o índice de mortes por quilômetro e o nível de desenvolvimento econômico dos estados. Constata-se que a situação da mortalidade no trânsito é um grave problema nacional, sobretudo nos estados mais pobres, onde os índices de mortes por veículo-quilômetro atingem números extremamente elevados. O fato positivo é que os números apontam para uma redução contínua do índice de mortes por quilômetro, que passou de 68,26 para 55,87 mortes por bilhão de quilômetros no país entre 2004 e 2008 (queda de 18,15%). Isso se deve ao aumento da quilometragem percorrida, função do aumento da frota, do crescimento econômico e de certa estabilização do número de mortes; este último em decorrência de ações em âmbito nacional implementadas pelo governo federal, bem como de ações específicas levadas a efeito em alguns estados. / This research estimated the value of the rate of deaths per kilometer traveled by the road vehicles fleet in Brazil and in each of the states of the federation, in the years 2004 to 2008. To determine the values of the average annual distance traveled by vehicles - parameter needed to estimate the rate of deaths per vehicle-kilometers - an appropriate methodology has been developed with reference on the amount of fuel sold by distributors in every state. The states were ranked according to all indexes associated with road fatalities, and the relationship between the rate of deaths per kilometer and the level of economic development of states, expressed by the motorization rate and the GDP per capita, is analyzed. It appears that the situation of traffic mortality is a serious national problem, especially in the poorest states, where the rate of deaths per vehicle-km reaches very high figures. The positive fact is that the numbers point to a continued reduction in the rate of deaths per kilometer, which decreased from 68.26 to 55.87 deaths per billion km in the country between 2004 and 2008 (a decrease of 18.15%). This is due to the increase on the distance traveled, a result of the increased fleet and economic growth, and also of some stabilization in the number of deaths; being the last a consequence of nationwide actions implemented by the federal government, and also of specific actions carried out in some states.

This study is conducted with the aims to develop a new ranking method for multi-criteria decision making problem with conflicting criteria. Such a problem has a set of Pareto solutions, where the act of improving a value of one solution will result in depreciating some of the others. Thus, in this type of problem, there is no unique solution. However, out of many available options, the Decision Maker eventually has to choose only one solution. With this problem as the motivation, the current study develops a compromise ranking algorithm, namely a trade-off ranking method. The trade-off ranking method able to give a trade-off solution with the least compromise compared to other choices as the best solution. The properties of the algorithm are studied in the thesis on several test cases. The proposed method is compared against several multi-criteria decision making methods with ranking based on the distance measure, which are the TOPSIS, relative distance and VIKOR. The sensitivity analysis and uncertainty test are carried out to examine the methods robustness. A critical criteria analysis is also done to test for the most critical criterion in a multi-criteria problem. The decision making method is considered further in a fuzzy environment problem where the fuzzy trade-off ranking is developed and compared against existing fuzzy decision making methods.

National soccer teams are currently ranked by soccer's governing body, the Federation Internationale de Football Association (FIFA). Although the system used by FIFA is thorough, taking into account many different factors, many of the weights used in the system's calculations are somewhat arbitrary. It is investigated here how the use of a statistical model might better compare the teams for ranking purposes. By treating each game played as a pairwise comparison experiment and by using the Bradley-Terry model as a starting point some suitable models are presented. A key component of the final model introduced here its ability to differentiate between friendly matches and competitive matches when determining the impact of a match on a teams ranking. Posterior distributions of the rating parameters are obtained, and the rankings and results obtained from each model are compared to FIFA's rankings and each other.