Integrating standard test collections in interactive IR instruction

Information retrieval experiments usually measure the average effectiveness of the IR methods developed. Direct use of an operational retrieval system has the shortcoming that the user is not given feedback about the effectiveness of queries. The Query Performance Analyser (QPA) for information retrieval systems is an interactive tool for the performance analysis of individual queries. On top of a standard test collection, it gives an instant visualisation of the performance achieved in a given search topic by any user-generated query. In addition to experimental IR research, the QPA can be used in user training to demonstrate the characteristics of and compare differences between IR systems and searching strategies. The experiences of using the tool in IR instruction are reported. The need to link instruction and research is underlined.


INTRODUCTION
The mainstream of research on information retrieval systems is based on the use of standard test collections.A test collection consists of a database, a large set of search topics and relevance assessments linking a small subset of database documents to each search topic.In this setting, the performance of a search system is examined by formulating a query for each search topic, by measuring effectiveness at standard points of operation, and by averaging effectiveness figures across all search topics.A typical goal is to show that some IR system/technique A is better than some other IR system/technique B in terms of average performance.The large number of search topics helps to verify the findings at an appropriate level of statistical significance.Direct use of an operational retrieval system in IR instruction has the shortcoming that the user is not given feedback about the effectiveness of queries.In principle, the searcher may judge each retrieved document and estimate the effectiveness of queries but this process is too clumsy and time consuming in the time frame of online training/testing.Effective learning and testing requires that the user is given more instant feedback about the effects of query modifications made.In this paper, we present the prototype and applications of the Interactive Query Performance Analyser for Information Retrieval Systems (Query Performance Analyser -QPA for short).The QPA is a tool for utilizing standard test settings in an interactive way: the user receives immediate feedback, both numeric and visual, on query performance, based on the relevance corpora.QPA is used both in research and teaching.It is an excellent tool for demonstrating how alternative query formulation strategies affect searching performance.The tool can also be used to build learning environments where students may perform exercises and learn IR techniques at their own pace.The goal of this article is to introduce QPA and tell about its use in IR instruction.In Section 2 we outline the basic ideas behind the Query Performance Analyser and present a description of the implementation.Section 3 presents how the QPA has been used and can be used in IR instruction.Finally, the challenges of further developing the Query Performance Analyser are discussed.

Structure and Implementation
The major components of the tool are: (1) a set of pre-defined search topics for a given document database, (2) relevance judgements explicating which documents match the relevance criteria of a search topic, (3) a module supporting query formulation, (4) a front-end system for query execution in selected IR systems, (5) a module for measuring and visualising the performance of user queries and (6) an administration interface.Databases, search topics and relevance data may be similar to those of the standard test collections.At present the QPA (version 5.1) is interfaced to, and utilises, the following external resources: 1) Retrieval Software (Boolean IR system TRIP, probabilistic IR system InQuery, the beta versions of Lemur and Terrier) 2) IR Test Collections (Finnish test collections containing 54,000 -433,000 newspaper articles, a TREC collection of 514,000 documents in English, a test collection of 161,000 newspaper articles in Swedish).3) Query Manipulation Resources (bilingual electronic dictionaries for word-by-word translations) 4) Applications for calculating recall-precision information for a query result set.
The QPA combines the database and software components of the IR environments listed above.It is accessible through a standard WWW browser: the implementation is based on the Java Servlet technology.Relevance data, search topics, user information and additional information needed for the functionality are stored in a relation database.A general flow of operations between the WWW browser side, Java servlet, SQL database and external resources is given in Figure 1.

Configuration of the tool
The tool can be used in two modes: in direct mode and in exercise mode.In direct mode the user of the tool defines his working environment by himself by selecting the target database, the search engine, the search task or topic, and the performance feedback types preferred.In the exercise mode, which is utilised mainly in IR instruction, the working environment is pre-defined by the course tutor.The student enters the query input page directly by activating a link on the exercise page.He is then served by the set of operations and feedback features selected by the tutor for that exercise.For example, performance feedback may be shown in its full extent, shown partially, or hidden completely.Configuring is easy and straightforward via the QPA administration interface.

Query formulation
The query formulation page contains only a description of the search topic, a vacant field for query input, and links to the query language help texts.It is up to the user to formulate the query in the syntax of the query language used.If some of the bilingual translation dictionaries have been switched on, query terms are automatically translated into the target language.The user is free to edit the original or the translated query, for example, to test the effects of removing ambiguous query terms.When the user clicks the "Submit query" button, the selected search system is logged in, the query is processed, and the set of retrieved documents is downloaded (access numbers and titles).Automatic translation facilities were designed for studying cross-lingual IR and are typically switched off in other uses.

Performance feedback
The front-end functions manage the process of running the queries and downloading documents.The QPA automatically downloads up to 800 matching documents in short form (identification numbers and titles).The list of documents retrieved is compared to the list of relevant documents to identify the ranks of relevant documents in the query result.This information is used to mark up relevant documents in the list of document titles displayed to the user and to create visualisations of the document list called relevance bar and recall pie (Figure 2).The same data is used to compute precision at standard recall levels and presented in the form of a P/R graph (Figure 3).The effects of query modifications can be easily perceived.The relevance bar and recall pie representations were especially designed for novice users.The recall pie immediately shows the success of the search.Colour coding in the relevance bar is used to indicate the relevance (green), topical marginality (grey) or non-relevance (white) of documents.The user may also click the bar to select the set of ten document titles displayed (ranks 1-10 in the picture, scrollable up to 800 titles).The full text of a document can be displayed by clicking the title.Precision-recall graph is a traditional way to represent averaged performance data.As default, the QPA displays the P/R graph of the n most recent queries and the best query of all earlier sessions.The P/R graphs of any queries can be attached to the co-ordinates as references.The best queries executed so far by any of the users are saved onto the "Hall of Fame" list.The "Hall of Fame" contains the best queries, user names and precision/recall levels achieved.The list is accessible to all users in direct mode but can be concealed partially or completely in the exercise mode.

Selections and search history
The user has an option to select documents on the search result page (Fig. 2) or when viewing individual documents.This functionality is advantageous especially when collecting a relevance corpus for a new topic.The user may select documents and assess them as relevant, irrelevant or undefined.Thus, she sees immediately which documents in the result list she already has assessed.Key data about all queries executed are stored and the user may browse his search history.It is also possible to select queries from the search history for visualisation to compare their performance (see Fig. 3).

USING THE QPA IN IR INSTRUCTION
Information retrieval instruction covers four main areas focusing on presenting (1) the context of information retrieval as a part of information seeking activities, (2) basic principles of information retrieval systems, (3) general search strategies applicable in all ordinary retrieval settings, and (4) specific search strategies for special retrieval settings and information sources.The main goal of instruction is to develop learners' practical capability to conduct searches and understand the heuristic nature of IR techniques

The QPA as a component of a learning environment
At the present stage of development, the QPA is a novel prototype tool for constructing IR learning environments.As a component of a learning environment, the QPA represents phenomenaria (see Perkins 1991), i.e., an area for presenting, observing and manipulating the phenomena of IR.The tool can also be seen as a construction kit for query modelling and analysis.It provides opportunities to simulate different kinds of settings of search topics, databases and retrieval systems.The QPA can be used for different purposes: (1) For an tutor in a classroom, the QPA is a tool to visualise the overall effectiveness of any query.It is easy to demonstrate how any reformulation of a query, or any change in the retrieval system affects performance.(2) For a designer of a learning environment, the QPA is a tool for creating searching exercises on which students may work at their own pace over the Web.(3) For an advanced student, the analyser is an environment for learning by doing, for example, the query formulation tactics in Boolean or bestmatch retrieval systems.In Boolean queries, visualising a search result with colour coding is an efficient tool to demonstrate the size and the content of the result set.For instance, in a database of news articles it is easy to illustrate how relevant articles occur in clusters in the chronologically ordered result set, sometimes quite far from the top.The observation that so many relevant documents are missed even by carefully designed queries can be a shocking experience for a user.In best-match queries, visualisation of search result is very useful when demonstrating the changes in the relevance ranking of documents from one query to another.It is much more difficult for the user to gain control over the search results in best-match systems.Nor is there an established corpus of expertise in everyday best-match searching comparable to that of Boolean searching.Thus, the QPA is also an excellent instrument for teachers to learn, demonstrate, and develop searching strategies for best-match systems.All teachers of IR at the Department have developed their personal ways to demonstrate IR phenomena with the Query Performance Analyser.Typical examples of phenomena that have been clarified by our teachers are: 1) Basic concepts and search techniques (differences in the performance of individual query terms, the effect of term truncation or database specific search elements, demonstrating the concepts of precision and recall...) 2) Boolean searching (the effect of query expansions, risks of conjunctive structures, the use of proximity operators…)  3) Best-match searching (how relevance ranking works, when ranking works…) 4) Comparison of Boolean and best-match searching (the differences between Boolean and best-match searching, situations where Boolean queries or best-match queries work better than the other, showing that queries have to be formulated differently for different types of IR systems…).
The list of examples emphasises that the Query Performance Analyser is appropriate for demonstrating both general IR phenomena and specific, database or search engine related phenomena.

Evaluation of the instructional use
Since 1998, the Query Performance Analyser has been used as a routine tool on several IR courses at the Department of Information Studies, University of Tampere.During the autumn term 1999, the first systematic field evaluation of the tool was conducted.The major focus was on how students experienced the learning situation and the capabilities of the tool (Halttunen and Sormunen 2000).Two studies investigated subsequent student performance (Halttunen 2003) and learning outcomes (Halttunen & Järvelin 2005).The main results these studies regarding the QPA are summarised below.For details and overall design and evaluation of two IR learning environments see the original research articles or Halttunen (2004).
The basic function of the system -performance feedback -was naturally seen to promote learning significantly.Feedback concerning the performance of one' s own query, the chance to freely reformulate the query and to further evaluate the effect of changes on performance was seen as a highly motivating and illuminating advancement.Furthermore, performance feedback allowed students to pay attention to the analysis and evaluation of query formulation and search keys.Feedback served as a scaffold to the next level of performance.This was contrasted with the heavy browsing and evaluation of search results, which is typical when operational databases are used for educational purposes.(Halttunen & Sormunen 2000.)The overall effectiveness of queries in the exercises was slightly better in the group using the QPA.The analysis of the distribution of effectiveness measures revealed that students in the QPA group achieved good performance in 23 cases, while the same performance was achieved in 12 cases in the traditional group.The difference between the groups was statistically significant.(Halttunen 2003.)On the other hand, the feedback mechanism could also fix students' attention on precision-recall estimates and some of them tried to improve on their previous results mechanically, without analysis and reflection of their preceding queries and results.In this respect, the feedback mechanism tempts searchers to pay attention to the performance measures achieved, not to the analysis of the search task situation.Displaying other searchers' successes creates a subtle competition and desire to improve one' s own search results.The search tasks in the test collections are well specified, and this exactness can be seen as an obstacle to learning.The linguistic expressions in the requests may be too predefined and artificial.Halttunen (2004) proposed and evaluated a solution to this problem by integrating search requests within the framework of simulated real-life activities or simulated work-tasks, which are proposed for the evaluation of interactive information retrieval systems (Borlund 2000).This kind of approach is similar to anchored instruction, an instructional approach developed by the Cognition and Technology Group at Vanderbilt (1992).Anchored instruction is strongly associated with situated learning and constructive learning environments.The major goal of anchored instruction is to overcome the problem of inert knowledge by teaching problem solving skills and independent thinking.Anchored instruction in a learning environment is intended to permit sustained exploration by students and teachers and enables them to understand the kinds of problems and opportunities that experts encounter and the knowledge that experts use as tools.
The development of IR skills was evaluated through performance learning outcomes assessment.The IR system and database used in the last session were new to all participants.There was a statistically significant difference between the groups in semantic knowledge errors.The traditional group made many more semantic knowledge errors than participants studying in the more QPA oriented, scaffolded and anchored learning environment.These errors were related to the process of transforming a search assignment into a query.Students from both learning environments made quite the same number of syntactic knowledge errors.It seemed that both groups could overcome problems with syntactic errors with active exploration, but semantic problems affected their overall performance.Students in the traditional environment were not able to achieve as good search results as participants in the experimental group.(Halttunen & Järvelin 2005.)Students' use of the QPA and attitudes towards it in instruction may be a result of an individual learner' s prior experience of IR or, for example, the learner' s personal learning style.This is also a matter of the instructional design of exercises, and the learning situation as a whole.The QPA leaves many options to the tutor to design a suitable learning environment.The tutor can modify the feedback mechanism, game-like features, help functions, and decisions concerning presentation and articulation of learning outcomes.

Figure 1 .
Figure 1.The flow of main operations in the Query Performance Analyser, version 5.1.

Figure 2 .
Figure 2. Search results page of the Query Performance Analyser.From top down: Main menu, search status data, document bar and recall pie, first ten titles with relevance indicators.

Figure 3 .
Figure 3. Performance visualisation as a Precision-Recall curve.