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NERD: Evaluating Named Entity Recognition Tools in the Web of Data

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NERD: Evaluating Named Entity Recognition Tools in the Web of Data

  1. 1. NERD: Evaluating Named Entity Recognition Tools in the Web of Data Giuseppe Rizzo <giuseppe.rizzo@eurecom.fr> Raphaël Troncy <raphael.troncy@eurecom.fr>
  2. 2. What is a Named Entity recognition task? A task that aims to locate and classify the name of a person or an organization, a location, a brand, a product, a numeric expression including time, date, money and percent in a textual document 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 2/21
  3. 3. Named Entity recognition tools 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 3/21
  4. 4. Differences among those NER extractors  Granularity  extract NE from sentences vs from the entire document  Technologies used  algorithms used to extract NE  supported languages  taxonomy of type of NE recognized  disambiguation (dataset used to provide links)  content request size  Response format 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 4/21
  5. 5. And ...  What about precision and recall?  Which extractor best fits my needs? 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 5/21
  6. 6. Seeks to find pros and cons of those extractors What is NERD? REST API1 ontology3 UI2 1 http://nerd.eurecom.fr/api/application.wadl 2 http://nerd.eurecom.fr/ 3 http://nerd.eurecom.fr/ontology 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 6/21
  7. 7. Showcase http://nerd.eurecom.fr Science: "Google Cars Drive Themselves", http://bit.ly/oTj8md (part of the original resource found at http://nyti.ms/9p19i8) 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 7/21
  8. 8. Evaluation 5 extractors using default configurations  Controlled experiment  4 human raters  10 English news articles (5 from BBC and 5 from The New York Times)  each rater evaluated each article for all the extractors  200 evaluations in total  Uncontrolled experiment  17 human raters  53 English news articles (sources: CNN, BBC, The New York Times and Yahoo! News)  free selection of articles Each human rater received a training1 1 http://nerd.eurecom.fr/help 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 8/21
  9. 9. Evaluation output t = (NE, type, URI, relevant) The assessment consists in rating these criteria with a Boolean value If no type or no disambiguation URI is provided by the extractor, it is considered false by default 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 9/21
  10. 10. Controlled experiment - dataset1 Categories: World, Business, Sport, Science, Health 1 BBC article and 1 NYT article for each category Average word number per article: 981 The final number of unique entities detected is 4641 with an average number of named entity per article equal to 23.2 Some of the extractors (e.g. DBpedia Spotlight and Extractiv) provide NE duplicates. We removed all duplicates do not bias the statistics 1 http://nerd.eurecom.fr/ui/evaluation/wekex2011-goldenset.tar.gz 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 10/21
  11. 11. Controlled experiment – agreement score Fleiss's kappa score1 Grouped by extractor Grouped by source Grouped by category 1 Joseph L. Fleiss. Measuring nominal scale agreement among many raters. Psychological Bulletin, 76(5):378–382, 1971 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 11/21
  12. 12. Controlled experiment – statistic result Overall statistics Grouped by extractor different behavior for different sources Grouped by category 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 12/21
  13. 13. Uncontrolled experiment - dataset 17 raters were free to select English news articles from CNN, BBC, The New York Times and Yahoo! News 53 news articles selected Total number of assessments = 94 and the assessment average number per user = 5.2 Each article assessed at least by 2 different tools The final number of unique entities detected is 1616 with an average number of named entity per article equal to 34 Some of the extractors (e.g. DBpedia Spotlight and Extractiv) provide NE duplicates. In order do not bias the statistics, we removed all duplicates 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 13/21
  14. 14. Uncontrolled experiment – statistic result (I) Overall precision Grouped by extractors 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 14/21
  15. 15. Uncontrolled experiment – statistic result (II) Grouped by category 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 15/21
  16. 16. Q. Which are the best NER tools ? Conclusion A. They are ... AlchemyAPI has obtained the best results in NE extraction and categorization DBpedia Spotlight and Zemanta showed ability to disambiguate NE in the LOD cloud Experiments across categories of articles did not show significant differences in the analysis. Published the WEKEX'11 ground-truth http://nerd.eurecom.fr/ui/evaluation/wekex2011-goldenset.tar.gz 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 16/21
  17. 17. Future Work (NERD Timeline) beginning core application uncontrolled experiment controlled experiment today REST API, release WEKEX'11 ground-truth release ISWC'11 ground truth NERD “smart” service: combining the best of all NER tools 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 17/21
  18. 18. ISWC'11 golden-set Do you believe it's easy to find an agreement among all raters? We'd like inviting to create a new golden-set during the ISWC'2011 poster and demo session. We will kindly ask each rater to evaluate two short parts of two English news articles with all extractors supported by NERD 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 18/21
  19. 19. Thanks for your time and your attention http://nerd.eurecom.fr @giusepperizzo @rtroncy #nerd http://www.slideshare.net/giusepperizzo 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 19/21
  20. 20. Fleiss ' Kappa chance agreement K = 1 fully agreement among all raters K = 0 (or lesser than) poor agreement 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 20/21
  21. 21. Fleiss ' kappa Interpretation Kappa Interpretation <0 Poor agreement 0.01 – 0.20 Slight agreement 0.21 – 0.40 Fair agreement 0.41 – 0.60 Moderate agreement 0.61 – 0.80 Substantial agreement 0.81 – 1.00 Almost perfect agreement 24 October 2011 Workshop on Web Scale Knowledge Extraction (WEKEX'11) - 21/21

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