Probabilistic Group Recommendation via Information Matching
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We present a probabilistic group recommendation model. And, also, a framework (alternative to Matrix Factorisation and Neighbourhood methods) that can be used to build personalised search, recommendation, people match, ad relevance matching models without reducing the dimensionality or computing explicit similarity.
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Probabilistic Group Recommendation via Information Matching
- 1. Probabilistic Group Recommendation via Information Matching Jagadeesh Gorla (@jgorla)1 Neal Lathia (@neal lathia)2 Stephen Robertson3 Jun Wang (@seawan)1 1University College London 2 University of Cambridge 3 Microsoft Research Cambridge
- 2. What is the problem? • Group recommendation • How to compute Pr(group relevance | group, activity)? • A probabilistic group recommendation model!
- 3. What is the problem? • Group recommendation • Individual users preferences? • Type of the group (group preferences)?
- 4. Type of the groups • Consensus preferences group • Relevant to every group member
- 5. Type of the groups • Shared preferences group • Relevant to every group member, or at-least not disliked by majority of the group members
- 6. Type of the groups • Split preferences group • Relevant to at-least one group member • e.g., Group of household members sharing the same TV but consume at different times
- 7. Individual vs. Group preferences • Individual preferences
- 8. Individual vs. Group preferences • Individual preferences
- 9. Individual vs. Group preferences What if they decide to watch a movie together?
- 10. Group recommendations? Merging individual preferences • Merge and create group profile • Generate recommendations for group
- 11. Group recommendations? Merging individual preferences • Merge and create group profile • Generate recommendations for group Problem: May present unwanted items, e.g.,Spartacus
- 12. Group recommendations? Merging individual preferences • Merge and create group profile • Generate recommendations for group Problem: May present unwanted items, e.g.,Spartacus Merging individual recommendations • Compute a list of recommendations for each member • Merge the individual lists
- 13. Group recommendations? Merging individual preferences • Merge and create group profile • Generate recommendations for group Problem: May present unwanted items, e.g.,Spartacus Merging individual recommendations • Compute a list of recommendations for each member • Merge the individual lists Problem: May lose preferences as part of a group
- 14. Group recommendations? Individual preference in a group may vary
- 15. Group recommendations? Individual preference in a group may vary Group recommendation should consider, • Individual preferences • Group preferences
- 16. Group recommendations? Individual preference in a group may vary Group recommendation should consider, • Individual preferences • Group preferences Hypothesis, • Group relevance is a function of “individual group member preferences”
- 17. Probabilistic model Some notation: 1 G is a set of users ({u1, u2 · · · , uh}) 2 Rg = 1 if the item is relevant to the group, and 0 otherwise 3 is a binary vector of individual relevance
- 18. Probabilistic model • Group relevance P(Rg = 1|G, i) ∝Rg h j=1 P(Rj, uj, i|Rg = 1) × h j=1 P(Rj|uj, i)
- 19. Probabilistic model • Group relevance P(Rg = 1|G, i) ∝Rg h j=1 P(Rj, uj, i|Rg = 1) × h j=1 P(Rj|uj, i) • Individual relevance
- 20. Probabilistic model • Group relevance P(Rg = 1|G, i) ∝Rg h j=1 P(Rj, uj, i|Rg = 1) × h j=1 P(Rj|uj, i) • Individual relevance
- 21. Probabilistic model • Group relevance P(Rg = 1|G, i) ∝Rg h j=1 P(Rj, uj, i|Rg = 1) × h j=1 P(Rj|uj, i) • Individual relevance • Least misery strategy: P(Rg = 1|G, i) ∝Rg min{P(R1 = 1|u1, i), · · · , P(Rh = 1|uh, i)}
- 22. Relevance to an individual Name: Jane Smith Sex: Female Age: 27 Location: Ipanema Product: Shoe Type: Formal Brand: Chanel Colour: Red
- 23. Relevance to an individual Name: Jane Smith Sex: Female Age: 27 Location: Ipanema Product: Shoe Type: Formal Brand: Chanel Colour: Red How to compute the relevance between Jane (“girl from Ipanema”) & Shoe?
- 24. Relevance to an individual Traditional approaches: • Neighbourhood approaches
- 25. Relevance to an individual Traditional approaches: • Neighbourhood approaches • Assume common feature space • matrix factorisation (e.g., PureSVD)
- 26. Relevance to an individual Traditional approaches: • Neighbourhood approaches • Assume common feature space • matrix factorisation (e.g., PureSVD) • Model features as a user/item
- 27. Relevance to an individual We want a framework with: • No explicit similarity
- 28. Relevance to an individual We want a framework with: • No explicit similarity • No common feature space
- 29. Relevance to an individual We want a framework with: • No explicit similarity • No common feature space • Interpretable features
- 30. Relevance to an individual We want a framework with: • No explicit similarity • No common feature space • Interpretable features Information Matching Model (IMM) or Bi-directional Unified Model
- 31. Idea ... • Find a best match for Me
- 32. Idea ... • Find a best match for Me • man −−−−→ woman man preferences
- 33. Idea ... • Find a best match for Me • man −−−−→ woman man preferences + man ←−−−−woman woman preferences
- 34. IMM U/Q/P α3 α2 α4 α1 . . . αl β3 β2 β4 β1 . . . βk Pro/D/P/Ad
- 35. IMM U/Q/P α3 α2 α4 α1 . . . αl β3 β2 β4 β1 . . . βk Pro/D/P/Ad
- 36. IMM U/Q/P α3 α2 α4 α1 . . . αl β3 β2 β4 β1 . . . βk Pro/D/P/Ad
- 37. IMM U1 U2 . . . α3 α2 α4 α1 . . . αl β3 β2 β4 β1 . . . βk Pr1 Pr2 . . .
- 38. It solves the problem of “Unified Model for Information Retrieval” S.E. Robertson, M.E. Maron and W.S. Cooper, The unified probabilistic model for IR, 1982.
- 39. Data Dataset Users Movies Ratings scale MovieLens1 1K 1.7K 100K [1-5] MovieLens2 6K 4K 1M [1-5] MoviePilot (Tr) 171K 24K 4.4M [0-100] MoviePilot (Eva) 594 811 4,482 [0-100] Number of households: 290
- 40. Evaluation Methodology Evaluation: • Individual recommendation • Household recommendation Individual recommendation • Randomly divide the data (60% training and 40% testing) – Movie Lens • Rank all the items • Precision@N, NDCG@N and Mean Average Precision (MAP)
- 41. Individual recommendation Figure: Recommending to Individuals.
- 42. Performance Loss Figure: PureSVD Figure: IMM
- 43. Conclusion • Can develop powerful group recommendation models within the framework • Take advantage of probabilistic modelling • Individual recommendation is crucial for group recommendation • Information Matching Model (IMM) framework can be used to build: • Search • Job matching • People matching (e.g., dating) • Product recommendation (ads, retail, etc.) • Targeted marketing
- 44. Thank You & Questions Acknowledgements: • This work has been sponsored by • My personal thanks to Ulrich Paquet ( )
- 45. Graphical Model αi zij dq βj ˆrdq rdq xi yj J θv i γv j gij hji l k d q