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Ken goldberg, gail de kosnik, kimiko ryokai (+ students) uc berkeley Opinion Space.

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Presentation on theme: "Ken goldberg, gail de kosnik, kimiko ryokai (+ students) uc berkeley Opinion Space."— Presentation transcript:

1 ken goldberg, gail de kosnik, kimiko ryokai (+ students) uc berkeley Opinion Space

2 Mission: To critically analyze and help shape developments in new media from para-disciplinary and global perspectives that emphasize humanities and the public interest. bcnm.berkeley.edu

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5 Opinion Space

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7 Open Discussion Question:

8 Opinion Space

9 Principal Component Analysis(1/4) Consider 2 propositions, each user is a point in a 2D space.

10 Principal Component Analysis (2/4) Now consider 3 propositions, each user is a point in 3D space Challenge: How to best project onto a screen for viewing data?

11 Principal Component Analysis (3/4) Different projections give different “views” of the data. PCA computes the projection that maximizes variance: Projection AProjection B

12 Principal Component Analysis (4/4) Maximum Variation Projection generalizes to n dimensions:

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14 Spatial Reputations: Assumptions Goal: design a reputation system for users in Opinion Space that is as fair and resistant to manipulation as possible Assumption: users are more likely to agree with comments made by near- by users Assumption: malicious users may be more interested in promoting a certain viewpoint than their own particular comment Idea: reward / emphasize comments that promote consensus from a diversity of users (“compelling”) = negative rating = positive rating

15 Spatial Reputations: Weighting Model Distance between users Score r’ of rating Spatial weighting model for comment ratings Model: transform comment ratings to reflect how valuable they are towards finding a compelling comment r ij ’ = 1 r ij ’ = -1

16 Sybil attacks: Two types of attacks –Create opinion profile most distant from the target’s profile (easily detectable) –Create uniformly distributed profiles (much more work) False feedback: to have maximum impact when rating similar users highly, forced to misrepresent ratings of five propositions. Can’t rate truthfully and unfairly inflate neighbor’s reputation at the same time. Whitewashing: Currently no functionality for detecting and preventing whitewashing. In the future, may use IP-tracking for this purpose. Analysis: Resisting Manipulation

17 Preliminary Analysis: Empirical As of May 5, over 11,000 ratings collected on 1,200 comments Users who gave the highest rating to a comment were on average 15% closer than users who gave the worst rating Raw comment ratings Number of ratings Ratings transformed by spatial reputations Number of ratings Correlation between rank aggregation methods

18 Opinion Space

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20 Opinion Space 2.0

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22 ken goldberg, goldberg@berkeley.edu 090909: Neutrality Symposium Please try it: http://opinion.berkeley.edu

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28 Opinion Space

29 Bias (Implicit Association) Test https://implicit.harvard.edu/implicit/

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31 … … … … Collaborative collaborative control models: MultiTasking Batch

32 Online Recommender Systems Pandora Amazon Netflix

33 The EigenTaste Algorithm Offline: –Compute eigenvectors and project users onto eigen plane. –Cluster and compute average ratings for each cluster. Online: –Collect ratings for objects in gauge set –Project onto the eigen plane –Find representative cluster –Recommend objects based on average ratings within that cluster

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