INEX 2012 Snippet Retrieval Track


Results of the 2012 round are available here.


The goal of the snippet retrieval track is to determine how best to generate informative snippets for search results. Such snippets should provide sufficient information to allow the user to determine the relevance of each document, without needing to view the document itself. Participating organisations will compare both the effectiveness of their focused retrieval systems as well as the effectiveness of their snippet generation systems, to others.

Changes from 2011

The following is an overview of the changes made to the track since last year:


The snippet retrieval track will use the INEX 2009 Wikipedia collection. Some topics will be recycled from previous ad hoc tracks, while others will be brand new.


Participating organisations will submit a ranked list of documents, and corresponding snippets. For those organisations uninterested in developing their own focused retrieval system, a reference run will be provided, consisting of a ranked list of documents, for which snippets should be created.

Each run will be submitted in the form of an XML file (format described below). Each submission should contain at least 20 snippets per topic, with a maximum of 180 characters per snippet. The snippets themselves may be created in any way you wish – they may consist of summaries, passages from the document, or any other text at all. Note that the document title will be shown alongside the snippet in the assessment software, so it is not necessary to include it within the snippet itself (although it is not disallowed).

Participants may submit more than one submission; however submissions must be ranked in order of importance, as not all submissions may be evaluated. Please note that participants will have to assess an additional package for each submission received.

Submission format

The DTD for the submission format is as follows.

<!ELEMENT inex-snippet-submission (description,topic+)>
<!ATTLIST inex-snippet-submission
  participant-id CDATA #REQUIRED
<!ELEMENT description (#PCDATA)>
<!ELEMENT topic (snippet+)>
<!ATTLIST topic
  topic-id CDATA #REQUIRED
<!ELEMENT snippet (#PCDATA)>
<!ATTLIST snippet

Each submission must contain the following:

Every run should contain the results for each topic, conforming to the following:

An example submission in the correct format is given below.

<?xml version="1.0"?>
<!DOCTYPE inex-snippet-submission SYSTEM "inex-snippet-submission.dtd">
<inex-snippet-submission participant-id="20" run-id="QUT_Snippet_Run_01">
    <description>A description of the approach used.</description>
    <topic topic-id="2011001">
        <snippet doc-id="16080300" rsv="0.9999">...</snippet>
        <snippet doc-id="16371300" rsv="0.9998">...</snippet>
    <topic topic-id="2011002">
        <snippet doc-id="1686300" rsv="0.9999">...</snippet>
        <snippet doc-id="1751300" rsv="0.9997">...</snippet>

Relevance assessments

Participating organisations will be required to perform assessment or other participants' submissions. For each submission received from a participating organisation, that organisation will be given an assessment package (the size of a single submission) to assess.

This year, both snippet-based and document-based assessment will be used. For each topic, the assessor will read through the details of the topic, after which they will read through each snippet, and determine whether or not the underlying document is relevant to the topic. After snippet-based assessment is complete, they will then assess the documents for relevance based on the full document text.

Because document-based assessment is being used in addition to snippet-based assessment this year, the number of topics and snippets has been reduced to keep the assessment load reasonable. There are 35 topics in total (down from 50 in 2011), and there will be 20 snippets/documents to assess for each topic (down from 100 snippets in 2011).


The primary evaluation metric, and the one which determines the ranking, is the geometric mean of recall and negative recall (GM), averaged over all topics: sqrt(TN/(TN+FP) * TP/(TP+FN)).

Other metrics include:


Because the track has had a late start, it will not be possible for any evaluation to be completed before the submission deadline for pre-proceedings papers. To ensure that some evaluation results are made available before the workshop itself, there will be two rounds of submissions. Round 1 will be due one month before the workshop, with the results aimed to be released a week ahead of the workshop. Submissions for Round 2 will be due one month after the workshop. Results from Round 2 will be included in the final proceedings.

The schedule is as follows:

Release of final topics:Jul 18
Submissions due:Oct 19
Assessment phase:November
Release of evaluation results:Early December


Matthew Trappett

Shlomo Geva

Andrew Trotman
University of Otago

Falk Scholer

Mark Sanderson

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