E ntity R esolution in N etwork D ata

1. Entity Resolution in Network Data Lise Getoor University of Maryland, College Park NetSci07 May 24, 2007

2. Entity Resolution • The Problem • The Algorithms • Graph-based Clustering (GBC) • Probabilistic Model (LDA-ER) • The Tool • The Big Picture

3. The Entity Resolution Problem James Smith John Smith “John Smith” “Jim Smith” “J Smith” “James Smith” “Jon Smith” Jonathan Smith “J Smith” “Jonthan Smith” Issues: • Identification • Disambiguation

4. before after InfoVis Co-Author Network Fragment

5. Entity Resolution in Networks • References not observed independently • Links between references indicate relations between the entities • Co-author relations for bibliographic data • To, cc: lists for email • Use relations to improve identification and disambiguation

6. Relational Identification Very similar names. Added evidence from shared co-authors

7. Relational Disambiguation Very similar names but no shared collaborators

8. Collective Entity Resolution One resolution provides evidence for another => joint resolution

9. Entity Resolution • The Problem • The Algorithms • Relational Clustering (RC-ER) • Bhattacharya and Getoor, DMKD’04, Wiley’06, TKDD’07 • Probabilistic Model (LDA-ER) • Experimental Evaluation • The Tool • The Big Picture

10. Objective Function • Minimize: weight for attributes similarity of attributes weight for relations 1 iff relational edge exists between ci and cj • Greedy clustering algorithm: merge cluster pair with max reduction in objective function Similarity of attributes Common cluster neighborhood

11. Relational Clustering Algorithm • Find similar references using ‘blocking’ • Bootstrap clusters using attributes and relations • Compute similarities for cluster pairs and insert into priority queue • Repeat until priority queue is empty • Find ‘closest’ cluster pair • Stop if similarity below threshold • Merge to create new cluster • Update similarity for ‘related’ clusters • O(n k log n) algorithm w/ efficient implementation CODE AND DATA AND DATA GENERATOR AVAILABLE HERE: http://www.cs.umd.edu/~indrajit/ER/

12. Entity Resolution • The Problem • Relational Entity Resolution • Algorithms • Relational Clustering (RC-ER) • Probabilistic Model (LDA-ER) • SIAM SDM’06, Best Paper Award • Experimental Evaluation • Query-time Entity Resolution

13. Probabilistic Generative Model for Collective Entity Resolution • Model how references co-occur in data • Generation of references from entities • Relationships between underlying entities • Groups of entities instead of pair-wise relations

14. α P θ R z β T a Φ A r V LDA-ER Model • Entity label aand group label z for each reference r • Θ: ‘mixture’ of groups for each co-occurrence • Φz:multinomial for choosing entity a for each group z • Va: multinomial for choosing reference r from entity a • Dirichlet priors with αand β

15. Approx. Inference Using Gibbs Sampling • Conditional distribution over labels for each ref. • Sample next labels from conditional distribution • Repeat over all references until convergence • Converges to most likely number of entities

16. Faster Inference: Split-Merge Sampling • Naïve strategy reassigns references individually • Alternative: allow entities to merge or split • For entity ai, find conditional distribution for • Merging with existing entity aj • Splitting back to last merged entities • Remaining unchanged • Sample next state for ai from distribution • O(n g + e) time per iteration compared to O(n g + n e)

17. Entity Resolution • The Problem • Relational Entity Resolution • Algorithms • Relational Clustering (RC-ER) • Probabilistic Model (LDA-ER) • Experimental Evaluation • Query-time Entity Resolution • ER User Interface

18. Evaluation Datasets • CiteSeer • 1,504 citations to machine learning papers (Lawrence et al.) • 2,892 references to 1,165 author entities • arXiv • 29,555 publications from High Energy Physics (KDD Cup’03) • 58,515 refs to 9,200 authors • Elsevier BioBase • 156,156 Biology papers (IBM KDD Challenge ’05) • 831,991 author refs • Keywords, topic classifications, language, country and affiliation of corresponding author, etc

19. Baselines • A: Pair-wise duplicate decisions w/ attributes only • Names:Soft-TFIDF with Levenstein, Jaro, Jaro-Winkler • Other textual attributes:TF-IDF • A*: Transitive closure over A • A+N: Add attribute similarity of co-occurring refs • A+N*: Transitive closure over A+N • Evaluate pair-wise decisions over references • F1-measure (harmonic mean of precision and recall)

20. ER Evaluation • RC-ER & LDA-ER outperform baselines in all datasets • Collective resolution better than naïve relational resolution • CiteSeer: Near perfect resolution; 22% error reduction • arXiv: 6,500 additional correct resolutions; 20% err. red. • BioBase: Biggest improvement over baselines

21. Trends in Synthetic Data Bigger improvement with • bigger % of ambiguous refs • more refs per co-occurrence • more neighbors per entity

22. Entity Resolution • The Problem • Relational Entity Resolution • The Algorithms • The Tool • H. Kang, M. Bilgic, L. Licamele, B. Shneiderman VAST06, IV07 • The Big Picture

23. D-Dupe: An Interactive Tool for Entity Resolution http://www.cs.umd.edu/projects/linqs/ddupe Novel combination of network visualization and statistical relational models well-suited to the visual analytic task at hand

24. Entity Resolution • The Problem • Relational Entity Resolution • The Algorithms • The Tool • The Big Picture

25. Putting Everything together….

26. Summary • In reality, want to be able to flexibly combine node, edge and graph-based inferences: • While there are important pitfalls to take into account (confidence and privacy), there are many potential benefits and payoffs Entity Resolution + Link Prediction + Collective Classification = Graph Identification

27. Thanks! http:www.cs.umd.edu/~getoor Work sponsored by the National Science Foundation, Google, KDD program and National Geospatial Agency