A recommender system is a subclass of information filtering system that seeks to predict the "rating" or "preference" a user would give to an item. These systems are present in a wide variety of applications and websites today. We can be aware of these recommendations when we are buying and articles similar to those we are looking for are suggested to us. However, they act in many other activities, such as in applications about restaurants and vacation trips. They also filter information from multimedia collections, such as Netflix or Amazon Prime. And furthermore, they are also present in browsers and they filter papers and books from repositories. They are subject to continuous research and improvement and the study of how these systems are being examined and evolve today is important because they literally filter the available information for us. This bibliometric study analyses the present-day research front on recommender systems. The chosen data source is the Web of Science bibliographic database and the study is performed following quantitative methods, using bibliometric techniques together with a qualitative assessment and interpretation of the most relevant research articles.

本研究分別利用書目對分析與共被引分析的方法，以資訊科學重要期刊之高引用期刊、作者與高被引期刊、作者作為研究對象，建構1991年至2010年之資訊科學知識地圖與研究前鋒。知識地圖的建構，採用文獻內容探勘工具(Content Analysis Toolkit for Academic Research，簡稱CATAR)作為分析工具，利用Web of Science下載書目資料，進行期刊與作者之書目對分析，以了解資訊科學高引用期刊與作者的叢集情況，進而探討資訊科學的知識結構。研究前鋒的建構則是透過Web of Science檢索共被引分析之數據，了解高被引期刊與作者之叢集情形，進而探討資訊科學之核心議題。 研究結果歸納如下： 一、資訊科學領域主要分成圖書資訊學與電腦科學兩大範疇。 二、資訊科學領域有跨學科之性質，許多期刊與作者研究的範圍不限於資訊科學領域，還包括了電腦科學、心理學、管理學、語言學、歷史學等。 三、資訊科學領域的共被引次數普遍偏低。 四、資訊科學領域核心議題的主要範圍為圖書資訊學、電腦科學、資訊科技與管理領域，子主題包含線上資訊、資訊檢索、資訊尋求行為、人機互動、自動化分類索引、書目計量學、科學計量學、網路計量學、引用文獻分析、研究前鋒研究、資訊視覺化、數位圖書館、資訊素養、圖書館服務、學術圖書館、科學計量學、電腦工程、電腦通訊、網際網路、資訊科技、資訊系統、管理。 五、1991年到2010年間，圖書館與資訊服務的自動化和資料庫設計與管理這兩個主題，在資訊科學領域中漸漸式微。 本研究結果可看出資訊科學的知識結構與研究前鋒，可應用於館藏規劃與評估，檢視圖書館的資訊科學領域館藏是否完整，並提供資訊科學領域的學者觀察學術研究趨勢之用。 / Through bibliographic coupling and co-citation analysis, this study builds on the knowledge map and research front of information science fields from 1991 to 2010. First, this research use CATAR which based on journal bibliographic coupling analysis and author bibliographic coupling to analyze the high citing journal and author in information science, and plot knowledge map on the subject of Information Science. Second, this research use journal co-citation analysis and author co-citation analysis where journal and author citing co-citation clusters to build the research front of Information Science. To result of the study reveal that： 1. Library and Information Science, Computer Science are the main disciplines in Information Science area. 2. The field of Information Science has the nature of interdisciplinary. The research area of any journals and authors are not limited to Information Science, and even likely to go beyond the subject of other disciplines, such as: Computer Science, Psychology, Management, Linguistics, History, etc. 3. Co-citation frequencies of Information Science high cited journals and authors are low. 4. The core area of Information Science field is Library and Information Science, Computer Science, Information Technology and Management. 5. During 1991 to 2010, library and information service automation, and design and management of database have been declining.

Objectives: The aim in this thesis has been to generate information relevant for strategic positioning and future evaluations within the scientific field of sport and exercise psychology. This has been done by request, and in collaboration with The Group of Sport and Exercise Psychology at the Institution of Psychology at the University of Umeå. Research questions:  (1) How does the cognitive structure within the field of sport and exercise psychology take shape with respect to research topics in current sport-psychological research, i.e. the research front? (2) How does the social structure within the field of sport and exercise psychology take shape with respect to formal scientific collaboration? Data: 879 articles published between 2008-2011 were used in this study. The population of articles were collected from a set of 5 core journals: International Journal of Sport Psychology, Journal of Applied Sport Psychology, Journal of Sport and Exercise Psychology, The Sport Psychologist, Psychology of Sport and Exercise. The original set was expanded by collecting relevant sport psychology articles from Scandinavian Journal of Medicine & Science in Sports and Journal of Sports Sciences. Methods: (1) The bibliometric indicator normalized bibliographic coupling combined with hierarchical agglomerative cluster analysis was used for mapping the research front. With this approach articles are basically clustered with respect to shared refererences, which in this context is understood as a measure of topical similarity. (2)  For the mapping of social structures a collaboration analysis was performed by extracting and visualizing social networks based on the bibliometric indicator coauthorship.     Results: (1) Identification and classification of 80 clusters based on topical similarity in collaboration with a subject expert. (2) Providing a map of formal scientific collaborations between countries based on coauthorship. (3) Providing a map of social networks based on coauthorships between individual researchers. (4) Identification and contextualization of central researchers based on production within the visualized coauthor network. The publications of each researcher were traced to corresponding clusters in the research front to gain information about in which subject areas and topics these central researchers publish. (5) Identification of research groups with high coauthor values, i.e. high intensity in their formal collaboration. Furthermore the publications from these groups were connected to corresponding clusters, i.e. giving information about in which subject areas and topics these groups publish.