Large-scale Social Recommendation Systems: Challenges and Opportunity

Large-Scale Social
Recommendation Systems:
Challenges And Opportunities
Mitul Tiwari!
!
Search, Network, and Analytics (SNA)!
LinkedIn
Who Am I
2
Outline
• About LinkedIn!
• Social Recommender Systems at LinkedIn!
• Social Graph Analysis!
• Virality in Social Recommender Systems!
• Scaling Challenges
3
Linkedin By The Numbers
4
225M members 2 new members/sec
Broad Range Of Products
5
Member Profile
6
Contacts
7
Talent Solutions
8
Job Search
9
Company Pages
10
Outline
• About LinkedIn!
• Social Recommender Systems at LinkedIn!
• Social Graph Analysis!
• Virality in Social Recommender Systems!
• Scaling Challenges
11
Linkedin Homepage
• Powered by
recommendations
12
Recommender Ecosystem
13
!
Similar  Profiles
Connections
News
Skill  Endorsements
Outline
• Social Recommender Systems at LinkedIn!
• LinkedIn Today: Recommend News!
• Jobs Recommendation!
• Related Searches Recommendation!
• Social Graph Analysis!
• Virality in Social Recommender Systems!
• Scaling Challenges
14
Linkedin Today: News Recommendation
• Objective: serve valuable professional news, leading to
higher engagement as measured by metrics such as CTR
15
News Recommendation: Explore/Exploit
16
item j from a set of candidates
User i
with
user features
(e.g., industry,
behavioral features,
Demographic
features,……)
(i, j) : response yijvisits
Algorithm selects
(click or not)
Which item should we select?
! The item with highest predicted CTR
! An item for which we need data to
predict its CTR
Exploit
Explore
Agarwal et. al 2012
News Recommendations: Challenges
• Drop in CTR wrt Time
17
News Recommendation: Challenges
• Same item shown to the same users: drop in CTR
18
News Recommendations: Revised Algorithm
• Explore/Exploit scheme!
• Explore: choose an item at random with a small probability (e.g., 5%)!
• Exploit: choose highest scoring CTR item (e.g., 95%)!
• Temporal smoothing: more weight to recent data!
• Impression discounting: discount items with repeat views!
• Segmented model: segment users in CTR estimation!
• Opportunity: Multi-arm bandit problem
19
Outline
20
• Social Recommender Systems at LinkedIn!
• LinkedIn Today: Recommend News!
• Jobs Recommendations!
• Related Searches Recommendation!
• Social Graph Analysis!
• Social Update Stream and Virality!
• Scaling Challenges
Jobs Recommendation
• Goal: recommend dream jobs to job
seekers!
• Challenges!
• Lag between view and application, offer,
acceptance!
• High level of expectations
21
Jobs Recommendation
22
17
Corpus StatsJob
User Base
Filtered
title
geo
company
industry
description
functional area
…
Candidate
General
expertise
specialties
education
headline
geo
experience
Current Position
title
summary
tenure length
industry
functional area
…
Similarity
(candidate expertise, job description)
0.56
Similarity
(candidate specialties, job description)
0.2
Transition probability
(candidate industry, job industry)
0.43
Title Similarity
0.8
Similarity (headline, title)
0.7
.
.
.
derived
Matching
Binary
Exact matches:
geo, industry,
…
Soft
transition
probabilities,
similarity,
…
Text
Transition probabilities
Connectivity
yrs of experience to reach title
education needed for this title
…
Ensemble
Scorings
Bhasin et. al 2012
Magic Is In Feature Engineering
• Open to relocation?!
• Region similarity based on profile or network!
• Region transition probability!
• Predict members’ propensity to migrate and
potential regions
23
What Should You Transition To And When
24
• Probability of holding a title wrt time: spikes 12 months aligned
Wang et. al, WWW’13
Job Seeking: Socially Contagious
25
[Zhang, 2012]
• Prob. of quitting increases as the #of recently left connected colleague
Outline
26
• Social Recommender Systems at LinkedIn!
• LinkedIn Today: Recommend News!
• Jobs Recommendation!
• Related Searches Recommendation!
• Social Graph Analysis!
• Social Update Stream and Virality!
• Scaling Challenges
Related Searches Recommendation
• Millions of Searches everyday!
• Help users to explore and refine their queries
27
Reda et. al, CIKM’12
Related Searches Recommendation
28
Related Searches Recommendations
• Signals!
• Collaborative Filtering!
• Query-Result Click graph!
• Overlapping terms!
• Length-bias!
• Ensemble approach for unified recommendation!
• Practical considerations
29
Related Searches Recommendations
• Signals!
• Collaborative Filtering!
• Query-Result Click graph!
• Overlapping terms!
• Length-bias!
• Ensemble approach for unified recommendation!
• Practical considerations!
• Opportunity: Build Personalized Search Recommendation
30
Outline
• About LinkedIn!
• Social Recommender Systems at LinkedIn!
• Social Graph Analysis!
• Virality in Social Recommender Systems!
• Scaling Challenges
31
Link Prediction Over Social Graph
32
Inmaps: Connection Graph
33
Connection Strength
• Measure strength of each connection!
• Applications!
• Introductions!
• Update stream relevance
34
Query-Result Clicks Graph
• Application: Related Searches correlated by result clicks
for related searches recommendation
Q1
Qn
R1
Rm
35
Skills Similarity Graph
• Graph of all co-occurrences between LinkedIn Skills
36
Skills
37
Find Influencers In Venture Capital?
38
Outline
• About LinkedIn!
• Social Recommender Systems at LinkedIn!
• Social Graph Analysis!
• Virality in Social Recommender Systems!
• Scaling Challenges
39
Suggested Skill Endorsement
40
Skills Endorsements
41
Viral Growth: 1B Skills Endorsements
• One of the fastest growing product in LinkedIn’s history
42
Skill Tagging
• Tagging: extract potential skills from
profile using skills taxonomy!
!
!
• Standardize skill phrase variants
Profile
Tokenize
SkillsTagger
Phrases
Skills
43
Skill Recommendation
• Predict a skill even if not
present in the profile!
• Based on likelihood of
member having a skill!
• Features: company, industry,
skills, ...
44
Profile
Tokenize
SkillsTagger
Phrases
Skills
Skills Classifier
Profile features
Recommended Skills
Suggested Skill Endorsements
• Binary Classification!
• Features!
• Company overlap, School overlap,
Industrial and functional area similarity,
Title similarity, Site interactions, Co-
interactions, ...
Candidate
generation
Classifier
Features	

- Company	

- Title	

- Industry	

...
Suggested
Endorsements
45
Social Recommendation And Tagging
SkillTagging
Skill Recommendation
Suggested Skill Endorsements
46
Skills Important For Data Scientists?
47
Outline
• About LinkedIn!
• Social Recommender Systems at LinkedIn!
• Social Graph Analysis!
• Virality in Social Recommender Systems!
• Scaling Challenges
48
Scaling Challenges: Related Searches Example
• Kafka: publish-subscribe messaging system!
• Hadoop: MapReduce data processing system !
• Azkaban: Hadoop workflow management tool!
• Voldemort: Key-value store
Metaphor
Hadoop
Search
Backend
Kafka
Voldemort
Related
Searches
Backend
Front
End
HDFS
49
Outline
• About LinkedIn!
• Social Recommender Systems at LinkedIn!
• Social Graph Analysis!
• Virality in Social Recommender Systems!
• Scaling Challenges
50
References
51
Acknowledgement
• Thanks to Data Team at LinkedIn: http://data.linkedin.com!
• We are hiring!!
• Contact: mtiwari[at]linkedin.com!
• Follow: @mitultiwari on Twitter
52
You!
Applied Reseacher/
Research Engineer
Questions?
53
1 of 53

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Large-scale Social Recommendation Systems: Challenges and Opportunity

  • 1. Large-Scale Social Recommendation Systems: Challenges And Opportunities Mitul Tiwari! ! Search, Network, and Analytics (SNA)! LinkedIn
  • 3. Outline • About LinkedIn! • Social Recommender Systems at LinkedIn! • Social Graph Analysis! • Virality in Social Recommender Systems! • Scaling Challenges 3
  • 4. Linkedin By The Numbers 4 225M members 2 new members/sec
  • 5. Broad Range Of Products 5
  • 11. Outline • About LinkedIn! • Social Recommender Systems at LinkedIn! • Social Graph Analysis! • Virality in Social Recommender Systems! • Scaling Challenges 11
  • 12. Linkedin Homepage • Powered by recommendations 12
  • 14. Outline • Social Recommender Systems at LinkedIn! • LinkedIn Today: Recommend News! • Jobs Recommendation! • Related Searches Recommendation! • Social Graph Analysis! • Virality in Social Recommender Systems! • Scaling Challenges 14
  • 15. Linkedin Today: News Recommendation • Objective: serve valuable professional news, leading to higher engagement as measured by metrics such as CTR 15
  • 16. News Recommendation: Explore/Exploit 16 item j from a set of candidates User i with user features (e.g., industry, behavioral features, Demographic features,……) (i, j) : response yijvisits Algorithm selects (click or not) Which item should we select? ! The item with highest predicted CTR ! An item for which we need data to predict its CTR Exploit Explore Agarwal et. al 2012
  • 17. News Recommendations: Challenges • Drop in CTR wrt Time 17
  • 18. News Recommendation: Challenges • Same item shown to the same users: drop in CTR 18
  • 19. News Recommendations: Revised Algorithm • Explore/Exploit scheme! • Explore: choose an item at random with a small probability (e.g., 5%)! • Exploit: choose highest scoring CTR item (e.g., 95%)! • Temporal smoothing: more weight to recent data! • Impression discounting: discount items with repeat views! • Segmented model: segment users in CTR estimation! • Opportunity: Multi-arm bandit problem 19
  • 20. Outline 20 • Social Recommender Systems at LinkedIn! • LinkedIn Today: Recommend News! • Jobs Recommendations! • Related Searches Recommendation! • Social Graph Analysis! • Social Update Stream and Virality! • Scaling Challenges
  • 21. Jobs Recommendation • Goal: recommend dream jobs to job seekers! • Challenges! • Lag between view and application, offer, acceptance! • High level of expectations 21
  • 22. Jobs Recommendation 22 17 Corpus StatsJob User Base Filtered title geo company industry description functional area … Candidate General expertise specialties education headline geo experience Current Position title summary tenure length industry functional area … Similarity (candidate expertise, job description) 0.56 Similarity (candidate specialties, job description) 0.2 Transition probability (candidate industry, job industry) 0.43 Title Similarity 0.8 Similarity (headline, title) 0.7 . . . derived Matching Binary Exact matches: geo, industry, … Soft transition probabilities, similarity, … Text Transition probabilities Connectivity yrs of experience to reach title education needed for this title … Ensemble Scorings Bhasin et. al 2012
  • 23. Magic Is In Feature Engineering • Open to relocation?! • Region similarity based on profile or network! • Region transition probability! • Predict members’ propensity to migrate and potential regions 23
  • 24. What Should You Transition To And When 24 • Probability of holding a title wrt time: spikes 12 months aligned Wang et. al, WWW’13
  • 25. Job Seeking: Socially Contagious 25 [Zhang, 2012] • Prob. of quitting increases as the #of recently left connected colleague
  • 26. Outline 26 • Social Recommender Systems at LinkedIn! • LinkedIn Today: Recommend News! • Jobs Recommendation! • Related Searches Recommendation! • Social Graph Analysis! • Social Update Stream and Virality! • Scaling Challenges
  • 27. Related Searches Recommendation • Millions of Searches everyday! • Help users to explore and refine their queries 27 Reda et. al, CIKM’12
  • 29. Related Searches Recommendations • Signals! • Collaborative Filtering! • Query-Result Click graph! • Overlapping terms! • Length-bias! • Ensemble approach for unified recommendation! • Practical considerations 29
  • 30. Related Searches Recommendations • Signals! • Collaborative Filtering! • Query-Result Click graph! • Overlapping terms! • Length-bias! • Ensemble approach for unified recommendation! • Practical considerations! • Opportunity: Build Personalized Search Recommendation 30
  • 31. Outline • About LinkedIn! • Social Recommender Systems at LinkedIn! • Social Graph Analysis! • Virality in Social Recommender Systems! • Scaling Challenges 31
  • 32. Link Prediction Over Social Graph 32
  • 34. Connection Strength • Measure strength of each connection! • Applications! • Introductions! • Update stream relevance 34
  • 35. Query-Result Clicks Graph • Application: Related Searches correlated by result clicks for related searches recommendation Q1 Qn R1 Rm 35
  • 36. Skills Similarity Graph • Graph of all co-occurrences between LinkedIn Skills 36
  • 38. Find Influencers In Venture Capital? 38
  • 39. Outline • About LinkedIn! • Social Recommender Systems at LinkedIn! • Social Graph Analysis! • Virality in Social Recommender Systems! • Scaling Challenges 39
  • 42. Viral Growth: 1B Skills Endorsements • One of the fastest growing product in LinkedIn’s history 42
  • 43. Skill Tagging • Tagging: extract potential skills from profile using skills taxonomy! ! ! • Standardize skill phrase variants Profile Tokenize SkillsTagger Phrases Skills 43
  • 44. Skill Recommendation • Predict a skill even if not present in the profile! • Based on likelihood of member having a skill! • Features: company, industry, skills, ... 44 Profile Tokenize SkillsTagger Phrases Skills Skills Classifier Profile features Recommended Skills
  • 45. Suggested Skill Endorsements • Binary Classification! • Features! • Company overlap, School overlap, Industrial and functional area similarity, Title similarity, Site interactions, Co- interactions, ... Candidate generation Classifier Features - Company - Title - Industry ... Suggested Endorsements 45
  • 46. Social Recommendation And Tagging SkillTagging Skill Recommendation Suggested Skill Endorsements 46
  • 47. Skills Important For Data Scientists? 47
  • 48. Outline • About LinkedIn! • Social Recommender Systems at LinkedIn! • Social Graph Analysis! • Virality in Social Recommender Systems! • Scaling Challenges 48
  • 49. Scaling Challenges: Related Searches Example • Kafka: publish-subscribe messaging system! • Hadoop: MapReduce data processing system ! • Azkaban: Hadoop workflow management tool! • Voldemort: Key-value store Metaphor Hadoop Search Backend Kafka Voldemort Related Searches Backend Front End HDFS 49
  • 50. Outline • About LinkedIn! • Social Recommender Systems at LinkedIn! • Social Graph Analysis! • Virality in Social Recommender Systems! • Scaling Challenges 50
  • 52. Acknowledgement • Thanks to Data Team at LinkedIn: http://data.linkedin.com! • We are hiring!! • Contact: mtiwari[at]linkedin.com! • Follow: @mitultiwari on Twitter 52 You! Applied Reseacher/ Research Engineer