Computing and Information Systems - Research Publications

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Start date: 2005 × End date: 2009 × Subject: Information Systems × Author: Moffat, Alistair × Author: Zobel, Justin ×

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Now showing 1 - 8 of 8
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    Load balancing for term-distributed parallel retrieval
    Moffat, A ; Webber, W ; Zobel, J (ACM, 2006-01-01)
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    Strategic System Comparisons via Targeted Relevance Judgements
    MOFFAT, A. ; WEBBER, W. ; ZOBEL, J. (ACM Press, 2007)
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    Precision-at-ten considered redundant
    Webber, W ; Moffat, A ; Zobel, J ; Sakai, T (ACM, 2008-12-15)
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    Improvements that don't add up: Ad-hoc retrieval results since 1998
    Armstrong, TG ; Moffat, A ; Webber, W ; Zobel, J (ACM, 2009-12-01)
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    Inverted files for text search engines
    Zobel, J ; Moffat, A (ASSOC COMPUTING MACHINERY, 2006)
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    A pipelined architecture for distributed text query evaluation
    Moffat, A ; Webber, W ; Zobel, J ; Baeza-Yates, R (SPRINGER, 2007-06)
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    Rank-Biased Precision for Measurement of Retrieval Effectiveness
    Moffat, A ; Zobel, J (ASSOC COMPUTING MACHINERY, 2009)
    A range of methods for measuring the effectiveness of information retrieval systems has been proposed. These are typically intended to provide a quantitative single-value summary of a document ranking relative to a query. However, many of these measures have failings. For example, recall is not well founded as a measure of satisfaction, since the user of an actual system cannot judge recall. Average precision is derived from recall, and suffers from the same problem. In addition, average precision lacks key stability properties that are needed for robust experiments. In this article, we introduce a new effectiveness metric, rank-biased precision , that avoids these problems. Rank-biased pre-cision is derived from a simple model of user behavior, is robust if answer rankings are extended to greater depths, and allows accurate quantification of experimental uncertainty, even when only partial relevance judgments are available.
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    Efficient online index construction for text databases
    Lester, N ; Moffat, A ; Zobel, J (ASSOC COMPUTING MACHINERY, 2008-08)
    Inverted index structures are a core element of current text retrieval systems. They can be constructed quickly using offline approaches, in which one or more passes are made over a static set of input data, and, at the completion of the process, an index is available for querying. However, there are search environments in which even a small delay in timeliness cannot be tolerated, and the index must always be queryable and up to date. Here we describe and analyze a geometric partitioning mechanism for online index construction that provides a range of tradeoffs between costs, and can be adapted to different balances of insertion and querying operations. Detailed experimental results are provided that show the extent of these tradeoffs, and that these new methods can yield substantial savings in online indexing costs.