Efthimis N. Efthimiadis

Conversational tagging in twitter

Users on Twitter, a microblogging service, started the phenomenon of adding tags to their messages sometime around February 2008. These tags are distinct from those in other Web 2.0 systems because users are less likely to index messages for later retrieval. We compare tagging patterns in Twitter with those in Delicious to show that tagging behavior in Twitter is different because of its conversational, rather than organizational nature. We use a mixed method of statistical analysis and an interpretive approach to study the phenomenon. We find that tagging in Twitter is more about filtering and directing content so that it appears in certain streams. The most illustrative example of how tagging in Twitter differs is the phenomenon of the Twitter micro-meme: emergent topics for which a tag is created, used widely for a few days, then disappears. We describe the micro-meme phenomenon and discuss the importance of this new tagging practice for the larger real-time search context.

Interactive query expansion: a user-based evaluation in a relevance feedback environment

A user-centered investigation of interactive query expansion within the context of a relevance feedback system is presented in this article. Data were collected from 25 searches using the INSPEC database. The data collection mechanisms included questionnaires, transaction logs, and relevance evaluations. The results discuss issues that relate to query expansion, retrieval effectiveness, the correspondence of the on-line-to-off-line relevance judgments, and the selection of terms for query expansion by users (interactive query expansion). The main conclusions drawn from the results of the study are that: (1) one-third of the terms presented to users in a list of candidate terms for query expansion was identified by the users as potentially useful for query expansion. (2) These terms were mainly judged as either variant expressions (synonyms) or alternative (related) terms to the initial query terms. However, a substantial portion of the selected terms were identified as representing new ideas. (3) The relationships identified between the five best terms selected by the users for query expansion and the initial query terms were that: (a) 34% of the query expansion terms have no relationship or other type of correspondence with a query term; (b) 66% of the remaining query expansion terms have a relationship to the query terms. These relationships were: narrower term (46%), broader term (3%), related term (17%). (4) The results provide evidence for the effectiveness of interactive query expansion. The initial search produced on average three highly relevant documents; the query expansion search produced on average nine further highly relevant documents. The conclusions highlight the need for more research on: interactive query expansion, the comparative evaluation of automatic vs. interactive query expansion, the study of weighted Web-based or Web-accessible retrieval systems in operational environments, and for user studies in searching ranked retrieval systems in general.

Characterization of national Web domains

During the last few years, several studies on the characterization of the public Web space of various national domains have been published. The pages of a country are an interesting set for studying the characteristics of the Web because at the same time these are diverse (as they are written by several authors) and yet rather similar (as they share a common geographical, historical and cultural context). This article discusses the methodologies used for presenting the results of Web characterization studies, including the granularity at which different aspects are presented, and a separation of concerns between contents, links, and technologies. Based on this, we present a side-by-side comparison of the results of 12 Web characterization studies, comprising over 120 million pages from 24 countries. The comparison unveils similarities and differences between the collections and sheds light on how certain results of a single Web characterization study on a sample may be valid in the context of the full Web.

A user-centred evaluation of ranking algorithms for interactive query expansion

The evaluation of 6 ranking algorithms for the ranking of terms for query expansion is discussed within the context of an investigation of interactive query expansion and relevance feedback in a real operational environment. The yardstick for the evaluation was provided by the user relevance judgements on the lists of the candidate terms for query expansion. The evaluation focuses on the similarities in the performance of the different algorithms and how the algorithms with similar performance treat terms.

User choices: a new yardstick for the evaluation of ranking algorithms for interactive query expansion

The performance of eight ranking algorithms was evaluated with respect to their effectiveness in ranking terms for query expansion. The evaluation was conducted within an investigation of interactive query expansion and relevance feedback in a real operational environment. This study focuses on the identification of algorithms that most effectively take cognizance of user preferences. User choices (i.e. the terms selected by the searchers for the query expansion search) provided the yardstick for the evaluation of the eight ranking algorithms. This methodology introduces a user-oriented approach in evaluating ranking algorithms for query expansion in contrast to the standard, system-oriented approaches. Similarities in the performance of the eight algorithms and the ways that these algorithms rank terms were the main focus of this evaluation. The findings demonstrate that the r-lohi, wpq, emim, and porter algorithms have similar performance in bringing good terms to the top of a ranked list of terms for query expansion. However, further evaluation of the algorithms in different (e.g. full-text) environments is needed before these results can be generalized beyond the context of the present study.

The Quality of Medical Evidence in Hematology-Oncology

PURPOSE The purpose of this study was to evaluate the quality of the medical evidence available to the clinician in the practice of hematology/oncology. METHODS We selected 14 neoplastic hematologic disorders and identified 154 clinically important patient management decision/interventions, ranging from initial treatment decisions to those made for the treatment of recurrent or refractory disease. We also performed a search of the scientific literature for the years 1966 through 1996 to identify all randomized controlled trials in hematology/oncology. RESULTS We identified 783 randomized controlled trials (level 1 evidence) pertaining to 37 (24%) of the decision/interventions. An additional 32 (21%) of the decision/interventions were supported by evidence from single arm prospective studies (level 2 evidence). However, only retrospective or anecdotal evidence (level 3 evidence) was available to support 55% of the identified decision/interventions. In a retrospective review of the decision/interventions made in the management of 255 consecutive patients, 78% of the initial decision/interventions in the management of newly diagnosed hematologic/oncologic disorders could have been based on level 1 evidence. However, more than half (52%) of all the decision/interventions made in the management of these 255 patients were supported only by level 2 or 3 evidence. CONCLUSIONS We conclude that level 1 evidence to support the development of practice guidelines is available primarily for initial decision/interventions of newly diagnosed diseases. Level 1 evidence to develop guidelines for the management of relapsed or refractory malignant diseases is currently lacking.

An exploration of the impact of computerized patient documentation on clinical collaboration

PURPOSE The purpose of this study was to explore the experience of experienced users of computerized patient documentation for the purpose of collaboration and coordination. A secondary analysis of qualitative data using Clarks theoretical framework of communication was conducted with the goal of bringing research findings into design. METHODS Physicians, nurses and administrative staff volunteered to participate in focus groups at 4 VA sites. Each focus group lasted 1.5h and targeted experience and issues with using computerized documentation. All focus groups were audio-taped and transcribed and submitted to extensive qualitative analysis using ATLAS, iterative identification of concepts and categories. The communication category was targeted for secondary theoretical analysis in order to deepen understanding of the findings. Clarks theory of communication, joint action and common ground heuristics was used to analyze concepts. RESULTS Key concepts included: (1) CPD has changed the way that narrative documentation is used in clinical settings to include more communication functions, strategies to establish joint action in both negative and positive ways; (2) functionality added to CPD to increase the efficiency of input may have increased the efficiency of CPD to support shared situation models, joint and action and the establishment of common ground; (3) new usage of CPD may increase tensions between clinical and administrative roles as the role of narrative is re-defined. CONCLUSIONS This study demonstrates how socio-technical systems co-evolve to support essential human function of coordination and collaboration. Users adapted the system in unique and useful ways that provide insight to future development.

Teaching and learning in information retrieval

A literature review of pedagogical methods for teaching and learning information retrieval is presented. From the analysis of the literature a taxonomy was built and it is used to structure the paper. Information Retrieval (IR) is presented from different points of view: technical levels, educational goals, teaching and learning methods, assessment and curricula. The review is organized around two levels of abstraction which form a taxonomy that deals with the different aspects of pedagogy as applied to information retrieval. The first level looks at the technical level of delivering information retrieval concepts, and at the educational goals as articulated by the two main subject domains where IR is delivered: computer science (CS) and library and information science (LIS). The second level focuses on pedagogical issues, such as teaching and learning methods, delivery modes (classroom, online or e-learning), use of IR systems for teaching, assessment and feedback, and curricula design. The survey, and its bibliography, provides an overview of the pedagogical research carried out in the field of IR. It also provides a guide for educators on approaches that can be applied to improving the student learning experiences.

Current research issues and trends in non-English Web searching

With increasingly higher numbers of non-English language web searchers the problems of efficient handling of non-English Web documents and user queries are becoming major issues for search engines. The main aim of this review paper is to make researchers aware of the existing problems in monolingual non-English Web retrieval by providing an overview of open issues. A significant number of papers are reviewed and the research issues investigated in these studies are categorized in order to identify the research questions and solutions proposed in these papers. Further research is proposed at the end of each section.

Interpreting user inactivity on search results

The lack of user activity on search results was until recently perceived as a sign of user dissatisfaction from retrieval performance, often, referring to such inactivity as a failed search (negative search abandonment). However, recent studies suggest that some search tasks can be achieved in the contents of the results displayed without the need to click through them (positive search abandonment); thus they emphasize the need to discriminate between successful and failed searches without follow-up clicks. In this paper, we study users’ inactivity on search results in relation to their pursued search goals and investigate the impact of displayed results on user clicking decisions. Our study examines two types of post-query user inactivity: pre-determined and post-determined depending on whether the user started searching with a preset intention to look for answers only within the result snippets and did not intend to click through the results, or the user inactivity was decided after the user had reviewed the list of retrieved documents. Our findings indicate that 27% of web searches in our sample are conducted with a pre-determined intention to look for answers in the results’ list and 75% of them can be satisfied in the contents of the displayed results. Moreover, in nearly half the queries that did not yield result visits, the desired information is found in the result snippets.