Evaluation Measures for Relevance and Credibility in Ranked Lists

Recent discussions on alternative facts, fake news, and post truth politics have motivated research on creating technologies that allow people not only to access information, but also to assess the credibility of the information presented to them by information retrieval systems. Whereas technology is in place for filtering information according to relevance and/or credibility, no single measure currently exists for evaluating the accuracy or precision (and more generally effectiveness) of both the relevance and the credibility of retrieved results. One obvious way of doing so is to measure relevance and credibility effectiveness separately, and then consolidate the two measures into one. There at least two problems with such an approach: (I) it is not certain that the same criteria are applied to the evaluation of both relevance and credibility (and applying different criteria introduces bias to the evaluation); (II) many more and richer measures exist for assessing relevance effectiveness than for assessing credibility effectiveness (hence risking further bias). Motivated by the above, we present two novel types of evaluation measures that are designed to measure the effectiveness of both relevance and credibility in ranked lists of retrieval results. Experimental evaluation on a small human-annotated dataset (that we make freely available to the research community) shows that our measures are expressive and intuitive in their interpretation

Cartographic Vandalism in the Era of Location-Based Games—The Case of OpenStreetMap and Pokémon GO

User-generated map data is increasingly used by the technology industry for background mapping, navigation and beyond. An example is the integration of OpenStreetMap (OSM) data in widely-used smartphone and web applications, such as Pokémon GO (PGO), a popular augmented reality smartphone game. As a result of OSM’s increased popularity, the worldwide audience that uses OSM through external applications is directly exposed to malicious edits which represent cartographic vandalism. Multiple reports of obscene and anti-semitic vandalism in OSM have surfaced in popular media over the years. These negative news related to cartographic vandalism undermine the credibility of collaboratively generated maps. Similarly, commercial map providers (e.g., Google Maps and Waze) are also prone to carto-vandalism through their crowdsourcing mechanism that they may use to keep their map products up-to-date. Using PGO as an example, this research analyzes harmful edits in OSM that originate from PGO players. More specifically, this paper analyzes the spatial, temporal and semantic characteristics of PGO carto-vandalism and discusses how the mapping community handles it. Our findings indicate that most harmful edits are quickly discovered and that the community becomes faster at detecting and fixing these harmful edits over time. Gaming related carto-vandalism in OSM was found to be a short-term, sporadic activity by individuals, whereas the task of fixing vandalism is persistently pursued by a dedicated user group within the OSM community. The characteristics of carto-vandalism identified in this research can be used to improve vandalism detection systems in the future

Web interaction environments : characterising Web accessibility at the large

Tese de doutoramento, Informática (Engenharia Informática), Universidade de Lisboa, Faculdade de Ciências, 2012Accessibility quality on the Web is essential for providing a good Web experience to people with disabilities. The existence of virtual ramps aid these users grasping and interacting withWeb content, just like the experience of those who are unimpaired. However, more often than not, Web pages impose accessibility barriers, usually centred on the unavailability of tailored content to specific perceptual abilities (e.g., textual description of images, enabling grasping information with assistive technologies), as well as on proper HTML structural elements that adequate the semantics of a Web page. When evaluating the accessibility quality of Web pages, the resulting analysis is often focused on a small sample set (e.g., a single Web page or a selection of pages from a Web site). While this kind of analysis gets the gist of accessibility quality, it misses the big picture on the overall accessibility quality of the Web. This thesis addresses the challenge of observing accessibility phenomena on the Web, through the experimental evaluation of large collections of Web pages. This resulted on new findings about the accessibility quality of the Web, such as its correlation with HTML element count, and the erroneous perception of accessibility quality by developers. Small-scale experiments have been verified also at large scale, such as the correlation between the usage of HTML templates and accessibility quality. Based on the challenges raised by the experimental evaluation, this thesis proposes a novel approach for large scale Web accessibility evaluation based on Linked Data, as well as the establishment of metrics to assess the truthfulness and coverage of automated evaluation methods.A qualidade da acessibilidade é um factor crucial para as pessoas com deficiências terem uma boa experiência de interacção com a Web.A qualidade da acessibilidade é um factor crucial para as pessoas com deficiências terem uma boa experiência de interacção com a Web. A existência de rampas virtuais ajuda estas pessoas a compreender e interagir com conteúdos Web, a par do que o utilizador comum já experiencia. Porém, a maioria das páginas Web ainda contêm barreiras à acessibilidade. Estas barreiras centram-se normalmente na indisponibilidade de conteúdos perceptíveis por diferentes tipos de capacidades (e.g., descrições textuais de imagens), bem como no uso incorrecto de elementos HTML de acordo com a semântica de uma página Web. Nos dias de hoje, a avaliação da qualidade de acessibilidade de páginas Web é ainda efectuada em pequena escala (e.g., uma página Web ou, no melhor caso, um conjunto de páginas representativas de um sítio Web). Apesar deste tipo de avaliações resultarem na compreensão de alguns fenómenos do estado da acessibilidade na Web, ainda não se sabe qual o seu impacto em larga escala. Esta tese discute os principais desafios na observação da acessibilidade da Web, tendo por base um conjunto de avaliações experimentais de colecções de grande dimensão de páginas Web. Destes estudos destacam-se as seguintes contribuições e resultados:a diferença drástica na interpretação dos avisos resultantes de avaliações de acessibilidade Web: um dos resultados principais da avaliação experimental em larga escala destaca a diferença na interpretação dos avisos (warnings) da aplicação de técnicas da norma WCAG, onde a interpretação optimista (i.e., a visão da maioria dos criadores de páginas Web) se distancia amplamente da interpretação conservadora (onde os avisos são interpretados como erros); a correlação entre a qualidade da acessibilidade de uma página Web e a sua complexidade: este mesmo estudo de larga escala revelou uma correlação entre a complexidade de uma página Web (no que diz respeito ao número de elementos HTML que contém) e a qualidade da acessibilidade. Quanto menor a complexidade de uma página Web, mais certa se torna a alta qualidade da acessibilidade dessa página; o benefício do uso de templates e sistemas de gestão de conteúdos na melhoria da acessibilidade de páginas Web: em ambos os estudos experimentais de acessibilidade foi detectada uma correlação entre a qualidade de acessibilidade das páginas Web e o uso de templates e sistemas de gestão de conteúdo. Esta propriedade foi verificada quer em pequena escala (sobre uma colecção de páginas Web da Wikipedia), quer em larga escala; o incumprimento das regras mais elementares e mais conhecidas da acessibilidade: estes estudos experimentais permitiram também verificar que, apesar de toda a envagelização e educação sobre as questões de acessibilidade na Web, a maioria das regras de acessibilidade são incessantemente quebradas pela maioria das páginas Web.Esta problemática verifica-se, em particular, nas regras de cumprimento de acessibilidade mais conhecidas, tal como por exemplo a disponibilidade de textos alternativos a conteúdos multimédia. Com base nestas experiências e resultados, esta tese apresenta um novo modelo de estudo da acessibilidade na Web, tendo por base o ciclo de estudos da Web em larga escala. Deste modelo resultaram as seguintes contribuições: um modelo para a avaliação distribuída de acessibilidade Web, baseado em propriedades tecnológicas e topológicas: foi concebido um modelo de avaliação de acessibilidade Web que permite a concepção de sistemas de avaliação com base em propriedades tecnológicas e topológicas. Este modelo possibilita, entre outras características, o estudo da cobertura de plataformas e avaliadores de acessibilidade, bem como da sua aplicação em larga escala; uma extensão às linguagens e modelos EARL e Linked Data, bem como um conjunto de definições para extrair informação destes: este modelo de avaliação de acessibilidade Web foi sustentado também pela sua concretização em linguagens e modelos já existentes para o estudo de acessibilidade (EARL) e da Web em larga escala (Linked Data), permitindo assim a sua validação; definição dos limites da avaliação de acessibilidade Web: por fim, este modelo de avaliação de acessibilidade permitiu também delinear uma metodologia de meta-avaliação da acessibilidade, na qual se poderão enquadrar as propriedades dos avaliadores de acessibilidade existentes. Todas estas contribuições resultaram também num conjunto de publicações científicas, das quais se destacam: Rui Lopes and Luís Carriço, A Web Science Perspective of Web Accessibility, in submission for the ACM Transactions on Accessible Computing (TACCESS), ACM, 2011; Rui Lopes and Luís Carriço, Macroscopic Characterisations of Web Accessibility, New Review of Hypermedia and Multimedia – Special Issue on Web Accessibility. Taylor & Francis, 2010; Rui Lopes, Karel Van Isacker and Luís Carriço, Redefining Assumptions: Accessibility and Its Stakeholders, The 12th International Conference on Computers Helping People with Special Needs (ICCHP), Vienna, Austria, 14-16 July 2010; Rui Lopes, Daniel Gomes and Luís Carriço, Web Not For All: A Large Scale Study of Web Accessibility, W4A: 7th ACM International Cross-Disciplinary Conference on Web Accessibility, Raleigh, North Carolina, USA, 26-27 April 2010; Rui Lopes, Konstantinos Votis, Luís Carriço, Dimitrios Tzovaras, and Spiridon Likothanassis, The Semantics of Personalised Web Accessibility Assessment, 25th Annual ACM Symposium on Applied Computing (SAC), Sierre, Switzerland, 22-26 March, 2010 Konstantinos Votis, Rui Lopes, Dimitrios Tzovaras, Luís Carriço and Spiridon Likothanassis, A Semantic Accessibility Assessment Environment for Design and Development for the Web, HCI International 2009 (HCII 2009), San Diego, California, USA, 19-24 July 2009 Rui Lopes and Luís Carriço, On the Gap Between Automated and In-Vivo Evaluations of Web Accessibility, HCI International 2009 (HCII 2009), San Diego, California, USA, 19-24 July 2009; Rui Lopes, Konstantinos Votis, Luís Carriço, Spiridon Likothanassis and Dimitrios Tzovaras, Towards the Universal Semantic Assessment of Accessibility, 24th Annual ACM Symposium on Applied Computing (SAC),Waikiki Beach, Honolulu, Hawaii, USA, 8-12 March 2009; Rui Lopes and Luís Carriço, Querying Web Accessibility Knowledge from Web Graphs, Handbook of Research on Social Dimensions of Semantic Technologies, IGI Global, 2009; Rui Lopes, Konstantinos Votis, Luís Carriço, Spiridon Likothanassis and Dimitrios Tzovaras, A Service Oriented Ontological Framework for the Semantic Validation of Web Accessibility, Handbook of Research on Social Dimensions of Semantic Technologies, IGI Global, 2009; Rui Lopes and Luís Carriço, On the Credibility of Wikipedia: an Accessibility Perspective, Second Workshop on Information Credibility on the Web (WICOW 2008), Napa Valley, California, USA, 2008; Rui Lopes, Luís Carriço, A Model for Universal Usability on the Web, WSW 2008: Web Science Workshop, Beijing, China, 22 April 2008; Rui Lopes, Luís Carriço, The Impact of Accessibility Assessment in Macro Scale Universal Usability Studies of the Web, W4A: 5th ACM International Cross-Disciplinary Conference on Web Accessibility, Beijing, China, 21-22 April 2008. Best paper award; Rui Lopes, Luís Carriço, Modelling Web Accessibility for Rich Document Production, Journal on Access Services 6 (1-2), Routledge, Taylor & Francis Group, 2009; Rui Lopes, Luís Carriço, Leveraging Rich Accessible Documents on the Web, W4A: 4th ACM International Cross-Disciplinary Conference on Web Accessibility, Banff, Canada, 7-8 May 2007.Fundação para a Ciência e a Tecnologia (FCT, SFRH/BD/29150/2006

Characterizing Online Vandalism: A Rational Choice Perspective

What factors influence the decision to vandalize? Although the harm is clear, the benefit to the vandal is less clear. In many cases, the thing being damaged may itself be something the vandal uses or enjoys. Vandalism holds communicative value: perhaps to the vandal themselves, to some audience at whom the vandalism is aimed, and to the general public. Viewing vandals as rational community participants despite their antinormative behavior offers the possibility of engaging with or countering their choices in novel ways. Rational choice theory (RCT) as applied in value expectancy theory (VET) offers a strategy for characterizing behaviors in a framework of rational choices, and begins with the supposition that subject to some weighting of personal preferences and constraints, individuals maximize their own utility by committing acts of vandalism. This study applies the framework of RCT and VET to gain insight into vandals' preferences and constraints. Using a mixed-methods analysis of Wikipedia, I combine social computing and criminological perspectives on vandalism to propose an ontology of vandalism for online content communities. I use this ontology to categorize 141 instances of vandalism and find that the character of vandalistic acts varies by vandals' relative identifiability, policy history with Wikipedia, and the effort required to vandalize

Social search in collaborative tagging networks : the role of ties

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How is encyclopaedia authority established?

I embarked on this research because I wanted to explore the basis of textual authority. Such an understanding is particularly important in a world where there is such an overload of information that it is a challenge for the public to identify which publications to choose when looking for specific information. I decided to look at the case of encyclopaedias because of the widespread belief that encyclopaedias are the ultimate authorities. I also made the choice based on the observation that, besides the research on Wikipedia, the scientific community seems to overlook encyclopaedias, despite of the role these latter play as key sources of information for the general public. Two theories are combined to serve as a framework for the thesis. On the one hand, there is the theory of cognitive authority as defined by Józef Maria Bocheński, Richard De George, and Patrick Wilson. On the other hand, there is the theory of quality as defined from the various frameworks recommended by librarians and information scientists on how to assess the quality of reference works. These two theoretical frameworks are used to deconstruct the concept of authority and to highlight aspects of authority which may be particularly worthy of investigation. In this thesis, studies were conducted on the following: (1) a literature review on the origin and evolution of encyclopaedia authority throughout the history of encyclopaedia, (2) a review of previous research pertaining to the quality and the authority of Wikipedia, (3) an analysis of the publishing and dissemination of science and technology encyclopaedias published in the 21st century throughout worldwide libraries, (4) a survey of perspective of encyclopaedia authors on the role of encyclopaedias in society and on the communication of scientific uncertainties and controversies, and (5) an analysis of book reviews towards a general assessment of encyclopaedia quality. The thesis illustrates how a concept such as authority which is typically taken for granted can actually be more complex and more problematic than it appears, thereby challenging widespread beliefs in society. In particular, the thesis pinpoints potential contradictions regarding the importance of the author and the publishers in ensuring encyclopaedia authority. On a theoretical level, the thesis revisits the concept of cognitive authority and initiates a discussion on the complex interaction between authority and quality. On a more pragmatic level, the thesis contributes towards the creation of guidelines for encyclopaedia development. As an exploratory study, the thesis also identifies a range of areas which should be of priority for future research

Assessing the quality of Wikidata referencing

Wikidata is a versatile and broad-based Knowledge Graph (KG) that leverages the power of collaborative contributions via an open wiki, augmented by bot accounts, to curate the content. Wikidata represents over 102 million interlinked data entities, accompanied by over 1.4 billion statements about the items, accessible to the public via a SPARQL endpoint and diverse dump formats. The Wikidata data model enables assigning references to every single statement. While the quality of Wikidata statements has been assessed, the quality of references in this knowledge graph is not well covered in the literature. To cover the gap, we develop and implement a comprehensive referencing quality assessment framework based on Linked Data quality dimensions and criteria. We implement the objective metrics of the assessment framework as the Referencing Quality Scoring System - RQSS. RQSS provides quantified scores by which the referencing quality can be analyzed and compared. Due to the scale of Wikidata, we developed a subsetting approach to creating a comparison platform that systematically samples Wikidata. We have used both well-defined subsets and random samples to evaluate the quality of references in Wikidata using RQSS. Based on RQSS, the overall referencing quality in Wikidata subsets is 0.58 out of 1. Random subsets (representative of Wikidata) have higher overall scores than topical subsets by 0.05, with Gene Wiki having the highest scores amongst topical subsets. Regarding referencing quality dimensions, all subsets have high scores in accuracy, availability, security, and understandability, but have weaker scores in completeness, verifiability, objectivity, and versatility. RQSS scripts can be reused to monitor the referencing quality over time. The evaluation shows that RQSS is practical and provides valuable information, which can be used by Wikidata contributors and WikiProject owners to identify the referencing quality gaps. Although RQSS is developed based on the Wikidata RDF model, its referencing quality assessment framework can be generalized to any RDF KG.James Watt Scholarship fundin

Fellow Travellers: What do users trust on recommender websites? A case study of TripAdvisor.com

Ph.DDOCTOR OF PHILOSOPH