On the Utility of Tags for Search and Navigation in Online Information Systems
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On the Utility of Tags for Search and Navigation in Online Information Systems On the Utility of Tags for Search and Navigation in Online Information Systems Presentation Transcript

  • Graz University of Technology On the Utility of Tags for Search and Navigation in Online Information Systems Christoph Trattner Knowledge Management Institute Graz University of Technology, Austria. Christoph Trattner Rigorosum 11.10.2012 1
  • Graz University of Technology What will this talk about Tagging Systems and in particular about Tags/tag clouds and their usefulness for the task of search and navigation. Christoph Trattner Rigorosum 11.10.2012 2
  • Graz University of Technology Definitions Tag = A short string, term or word that describes or categorizes an online resource and that is applied by a person or a set people Tagging System = An online information system that allows the users to apply tags to resources of the system. Christoph Trattner Rigorosum 11.10.2012 3 View slide
  • Graz University of Technology What was the motivation of my work?. Christoph Trattner Rigorosum 11.10.2012 4 View slide
  • Graz University of Technology Motivation? What I recognized when I started my PhD work 3 years ago was the fact that a lot of modern online information systems used tagging functionality to categorize or describe content and… to build simple user interfaces on the top-of this light- weight meta-data structures. Christoph Trattner Rigorosum 11.10.2012 5
  • Graz University of Technology. Christoph Trattner Rigorosum 11.10.2012 6
  • Graz University of Technology Tags. Christoph Trattner Rigorosum 11.10.2012 7
  • Graz University of Technology Interestingly There is a lot of work, Analysis of Tagging Systems [Hammond et al.] [Golder and Huberman] [Marlow et al.] [Halphin et al.] [Shen and Wu] Tags vs. Keywords vs. Named Entities (semantic/structure) There is hardly any research [Krause et al.] [Benz et al.] [Heymann et al.] that investigates the usefulness Tagging Motivation and Behavior of tags or tag clouds for the [Heckner et al.] [Ames and Naaman] [Strohmaier et al.] task of search and navigation [Körner et al.] in tagging systems Tag Cloud Construction & Visualization [Montero and Solana] [Kautz et al.] [Rivadeneira et al.] [Kaser and Lemire] [Seifert et al.] Utility of Tag Clouds for Search Result Summarization [Kuo et al.] [Koutrika et al.] [Sinclair et al.]. Christoph Trattner Rigorosum 11.10.2012 8
  • Graz University of Technology Problem Statement The problem we are facing in this dissertation is the lack of knowledge about the usefulness and the efficiency of tags and corresponding state-of-the-art tag- constructs such as tag clouds for the task of search and navigation in tagging systems.. Christoph Trattner Rigorosum 11.10.2012 9
  • Graz University of Technology Research Questions RQ1: To what extent are tags/tag clouds useful for (efficient) navigation in tagging systems? RQ2: To what extent are tags/tag clouds useful for search? RQ3: To what extent are tags/tag clouds more useful/efficient for search/navigation than other tag-alike meta-data such as keywords or search query-terms? RQ4: To what extent can we build better tag-based browsing constructs that support efficient search/navigation in tagging systems?. Christoph Trattner Rigorosum 11.10.2012 10
  • Graz University of Technology Ok, lets start….. Christoph Trattner Rigorosum 11.10.2012 11
  • Graz University of Technology Research Question 1: To what extent are tags/tag clouds useful for (efficient) navigation in tagging systems? Helic, D., Trattner, C., Strohmaier, M. and Andrews, K. 2010. On the Navigability of Social Tagging Systems. In Proceedings of the Second IEEE International Conference on Social Computing (SocialCom 2010), Minneapolis, Minnesota, USA, pp. 161-168.. Christoph Trattner Rigorosum 11.10.2012 12
  • Graz University of Technology Modeling tagging systems as graphs To answer the question to what extent tags/tag clouds are useful for navigation in tagging systems we modeled tagging systems as bipartite graphs Tags Resources (= Text Documents, Images, URLs). Christoph Trattner Rigorosum 11.10.2012 13
  • Graz University of Technology Defining Navigability A network is navigable iff: There is a short path between all or almost all pairs of nodes in the network. [Kleinberg 1999] Formally: 1. There exists a giant component (> 90%) 2. The effective diameter is low (bounded by log n)J. Kleinberg. The small-world phenomenon: An algorithmic perspective. Proc. 32nd ACM Symposium on Theory of Computing, 2000. Also appears as Cornell Computer ScienceTechnical Report 99-1776 (October 1999). Christoph Trattner Rigorosum 11.10.2012 14
  • Graz University of Technology Are tags useful for navigation? Austria-Forum: 32,245 annotations, 12,837 resources Results: BibSonomy: 916,495 annotations, 235,339 resources CiteULike: 6,328,021 annotations, 1,697,365 resources In general tags form networks which are navigable. Christoph Trattner Rigorosum 11.10.2012 15
  • Graz University of Technology Are tags useful for efficient navigation? . Tagging networks are navigable power-law networks. For power law Results: networks, efficient sub-linear decentralised navigation algorithms exist. In general tags form networks which are also efficiently navigable. Christoph Trattner Rigorosum 11.10.2012 16
  • Graz University of Technology But how about tag clouds? Tag Cloud Size n topN resources (topN most common algorithm) Pagination of resources / tag k resources shown / page (reverse chronological ordering). Christoph Trattner Rigorosum 11.10.2012 17
  • Graz University of Technology Are tag clouds useful for navigation? Tag Cloud Size . Pagination Results: Limiting the tag cloud size n to practically feasible sizes (e.g. 5, 10, or more) does not influence navigability (this is not very surprising). In general tag clouds do not BUT: Limiting the out-degree of high frequency tags k (e.g. through pagination provide the possibility to with resources sorted in reverse-chronological order) leaves the network vulnerable to fragmentation. This destroys navigability of prevalent approaches in navigate to all resources to tag clouds. a tagging system. Christoph Trattner Rigorosum 11.10.2012 18
  • Graz University of Technology Research Question 2: To what extent are tags/tag clouds useful for search? Trattner, C., Lin, Y., Parra, D., Yue, Z., Real, W. and Brusilovsky, P. 2012. Evaluating Tag-Based Information Access in Image Collections. In Proceedings of the 23rd ACM Conference on Hypertext and Social Media (HT 2012), ACM, New York, NY, USA, pp. 113-122.. Christoph Trattner Rigorosum 11.10.2012 19
  • Graz University of Technology Methodolgy A controlled user study with 24 participants With three different types of search interfacesBaseline Tag Cloud Faceted Tag Cloud1 2 3. Christoph Trattner Rigorosum 11.10.2012 20
  • Graz University of Technology Dataset  ~ 2,000 images  ~ 4,200 tags  ~ 16,000 tag assignments Interesting Fact: Tags were generated by ~100 users from Amazon Mechanical Turk. Christoph Trattner Rigorosum 11.10.2012 21
  • Graz University of Technology Evaluation: Look-up TaskLook-up task. Christoph Trattner Rigorosum 11.10.2012 22
  • Graz University of Technology Evaluation: Exploratory Search TaskExploratroy searchtask. Christoph Trattner Rigorosum 11.10.2012 23
  • Graz University of Technology Results: Performance Variables: Question: What interface performs best? • Total Actions • Search Time 1 2 3  Look-up: no sign. differences between interfaces Results:  Exploratory: Tag Cloud Interface out-performs baselineTag cloud interface The Faceted Tag Cloud Interface almost as slow as baseline significantly outperforms the baseline (no-tag) interface. Christoph Trattner Rigorosum 11.10.2012 24
  • Graz University of Technology Results: Preference and Rating Question: What was the preference of the users? • Post-questionair was handed out to the subjects with overall 7 questions. No tags tags Question: How are the interfaces rated? Results: The Tag cloud interfaces are Scale: 1 = very bad….5=very good significantly higher rated than the non-tag interface. Christoph Trattner Rigorosum 11.10.2012 25
  • Graz University of Technology Research Question 3: To what extent are tags/tag clouds more useful/efficient for search/navigation than other tag-alike meta-data such as keywords or search query-terms? Trattner, C. 2011. Linking Related Content in Web Encyclopedias with search query tag clouds. In the International Journal on WWW/Internet, Volume 9, Issue 2 (IJWI), pp. 33-55. Helic, D., Körner, C., Granitzer, M., Strohmaier, M. and Trattner, C. 2012. Navigational Efficiency of Broad vs. Narrow Folksonomies. In Proceedings of the 23rd ACM Conference on Hypertext and Social Media (HT 2012), ACM, New York, NY, USA, pp. 63-72.. Christoph Trattner Rigorosum 11.10.2012 26
  • Graz University of Technology Example: Austria-Forum  In Austria-Forum tags/tag clouds are used to link related content  Since the tagging system is in a early adopting phase search query terms are used. Christoph Trattner Rigorosum 11.10.2012 27
  • Graz University of Technology Are query terms more navigable than tags? Results: Results: Both user tag and query tag networks show a large connected component Both show an ED that is bounded byOn a network-theoretic level we log(N) find that the AF user tags and query tags are efficiently navigable. Christoph Trattner Rigorosum 11.10.2012 28
  • Graz University of Technology And how efficient are they for humans? To that end, we implemented a decentralized search algorithm that simulates human-like tag-based navigation by inducing a hierarchy out of the tag-resource network [Helic 2011] [Trattner 2012]. Tag hierarchy Tag (Cloud) network Trattner, C., Singer, P., Helic, D. and Strohmaier, M.: Exploring the Differences and Similarities of Hierarchical Decentralized Search and Human Navigation in Information-networks, In Proceedings of the 12th International Conference on Knowledge Management and Knowledge Technologies, ACM, New York, NY, USA, 2012. Helic, D., Strohmaier, M., Trattner, C., Muhr M. and Lermann, K.:Pragmatic Evaluation of Folksonomies, In Proceedings of the 20th international conference on World wide web, ACM, New York, NY, USA, 417-426, 2011.. Christoph Trattner Rigorosum 11.10.2012 29
  • Graz University of Technology What are the results? Additionally to this a user study was conducted to determine the quality of the query tags, showing no sign. difference. Results: From simulations we find that the query tags are better suited for navigation than user tags. Christoph Trattner Rigorosum 11.10.2012 30
  • Graz University of Technology Example: Mendeley Tags  WeKeyword =A short term or string (typical Keywordscontrolled vocabulary)assigned by a single user. Christoph Trattner Rigorosum 11.10.2012 31
  • Graz University of Technology Are keywords more navigable than tags? #hops success rate #hops success rate Stretch= #hops/shortest path Keywords Results: Tags Results: Our Greedy Navigator (= Simulator)simulations we find 1- tags are With needs on average that more efficient for navigation than click more with keywords to reach the target node than with tags keywords. Christoph Trattner Rigorosum 11.10.2012 32
  • Graz University of Technology “Since we observed that tagging systems only support efficient navigation through tags if no user interface limitations are considered, we had the idea to invent a number of new approaches that support more efficient navigation with tags.”. Christoph Trattner Rigorosum 11.10.2012 33
  • Graz University of Technology Research Question 4: To what extent can we build better tag-based browsing constructs that support efficient search/navigation in tagging systems? Trattner, C., Helic, D. and Strohmaier, M. 2011. On the Construction of Efficiently Navigable Tag Clouds Using Knowledge From Structured Web Content. In the Journal of Universal Computer Science (JUCS), Volume 17, Issue 4, pp. 565-582. Trattner, C. 2011. Improving the Navigability of Tagging Systems with Hierarchically Constructed Resource Lists: A Comparative Study. In Proceedings of the 33rd International Conference on Information Technology Interfaces (ITI 2011), IEEE, Cavtat / Dubrovnik, Croatia, pp. 173-178. Trattner, C., Körner, C. and Helic, D. 2011. Enhancing the Navigability of Social Tagging Systems with Tag Taxonomies. In Proceedings of the 11th International Conference on Knowledge Management and Knowledge Technologies (I-Know 2011). ACM, New York, NY, USA, pp. 18:1-18:8. Trattner, C. 2011. Improving the Navigability of Tagging Systems with Hierarchically Constructed Resource Lists and Tag Trails. In the Journal of Computing and Information Technology (CIT), Volume 19, Issue 3, pp. 155-167.. Christoph Trattner Rigorosum 11.10.2012 34
  • Graz University of Technology How can we enhance Tag Cloud navigability?. Christoph Trattner Rigorosum 11.10.2012 35
  • Graz University of Technology Idea Through dynamic resource list construction!. Christoph Trattner Rigorosum 11.10.2012 36
  • Graz University of Technology Approach Link1 Link1 Link1 Link4 Tag Link2 Link2 Link2 Tag Tag Tag Link10 Link4 Link4 Link4 Link11 Link5 Link5 Link5 Link3 Resource x Resource y Resource x Resource y Static Resource List Construction Dynamic Resource List Construction Instead of calculating the resource list statically, we calculate the resource list in a dynamic and resource-specific manner => On each click on a particular tag a different resource list is generated. Christoph Trattner Rigorosum 11.10.2012 37
  • Graz University of Technology Approach: Hierarchical Resource List Construction. Christoph Trattner Rigorosum 11.10.2012 38
  • Graz University of Technology Results Giant Component Random Similarity Hierarchical Results: Only the random approach and the hierarchical resource list calculation approach show a large connected component. Christoph Trattner Rigorosum 11.10.2012 39
  • Graz University of Technology Results Hierarchically Constructed Resource List Results: We find tag clouds calculating the resource list inUser Study a hierarchical manner Simulations are better suited for navigation. Christoph Trattner Rigorosum 11.10.2012 40
  • Graz University of Technology …ok lets come to an end . Christoph Trattner Rigorosum 11.10.2012 41
  • Graz University of Technology Summary of Contributions 1. The review of the utility of tags for the task of search and navigation in tagging systems 2. The navigational review of tags compared to other tag-alike meta-data structures such as keywords and search query terms 3. The introduction of (a number) of new approach(es) to support more efficient tag-based navigation in tagging systems. Christoph Trattner Rigorosum 11.10.2012 42
  • Graz University of Technology Thank you! Christoph Trattner Email: ctrattner@iicm.edu Web: www.christophtrattner.info Twitter: @ctrattner Sponsors:. Christoph Trattner Rigorosum 11.10.2012 43