CS-595 - Reputation

Emily Murray Dominic Metzger Kian Wilcox Kevin Almeroth

Definitions of Reputation

   a tool to predict behavior based on past actions and characteristics (Dingledine et. al) A general opinion, social evaluation towards a:     Person Group Organization A product Reputation systems: attempt to attach a reputation to an identity and make an ongoing assessment of that reputation (eBay, Slashdot, E2…etc.)

Social Exchange

 Evolutionary advantage: reciprocal altruism, tit-for-tat are stable strategies (Trivers, 1971; Axelrod,1984)  Evolutionary problem: recognizing cheaters (someone who takes a benefit without paying the cost, Cosmides (1989)  Easy in repeated, face to face interactions  Harder in anonymous interactions

Environment of Evolutionary Adaptedness

  Small groups (30-100 persons) Very social —evolution of large neocortex   Hierarchies facilitate group living Status largely determined by size in ‘lower’ species, but by social “Machiavellian Intelligence” in both human and non-human primates  Gossip is main source of important info about conspecifics (in humans)

Types of info conveyed

 Who’s a good mating partner  Who is weak  **Who you can trust/who is a good exchange partner  Who is aggressive/needs to be taken out  Who screwed up by eating that poisonous root

What a good rep buys you (in EEA)

 friends →alliances→coalitions  Quality mates (sex partners)  Deference  Food  Privileged information  Status, status, status

What a bad rep costs you (then and now)

  No one to trade with/no one sharing with you Social exclusion, ostracism, isolation →→ *No food *No mates *No genes propigated *death

In business interactions

 Good reps yield success (i.e. more $$)  (why PR people make so much $$)  Trust is most important reputation to have   Regulation not really through law, but via market mechanisms of trust and reputation Adam Smith’s “invisible hand”  Trust leads to mutually beneficial interactions and cheaper transactions

Reputations on

  Why do we care?

 Because it leads to trust Why do we care about trust?

 Because trust -> money

Trust -> Money Resnick et. al. [2]

 “STRONG” (1) & “NEW” (7) sellers  H1: Buyers are willing to pay more to a seller with a strong positive reputation than sellers without such a reputation  H2: The new sellers with negative feedback will reap lower profits than those without negative feedback. The new seller with two negative feedbacks will reap lower profits than those with just one negative feedback.

What they were selling

Results

 buyers are willing to pay 8.1% more for lots sold by STRONG than NEW (~ $1.23 more)  a seller with a strong reputation received a price premium, even holding constant quality of goods, skill at listing, and responsiveness to inquiries, all potential confounds in previous observational studies.

 buyers appeared not to pay sufficient attention to negative feedback for relatively new sellers

More results

 http://www.si.umich.edu/~presnick/papers/po stcards/PostcardsFinalPrePub.pdf

Success of ‘s Reputation System

 A Happy Little World  Percentage of negative feedback is less than 1% for both buyers and sellers [1]

Balances of Power: Inequality of Peers

  Buyer often in less powerful position Leads to:   Problem of negative feedback   Implicit threat or retaliation Have to deal with other party’s reaction Leads to: artificially low rate of negative feedback and fraud

Balances of Power - cont.

 Solutions:    Seller provides the first feedback [1] Make the total number of transactions visible [2] Blind Reviews   Decouple service and feedback trust [8] Why doesn’t eBay improve this?

 Desire to appear to provide a more trustworthy marketplace

Phishing & Identity Theft

  Phishing attack: Convincing a person to place trust in a criminally untrustworthy party by masquerading as a trusted party.

Example:  http://www.identitytheftsecrets.com/videos/wellsf argo.html

Fraud

 Fraud (as defined by pres of eBay):   Paying for an item and never receiving it Receiving an item that is less than what is described (ex. buying a solid gold necklace, but receiving a cheap plated one instead)

Fraud Example

 In mid-2000, a group of people engaged in eBay auctions and behaved well. As a result, their trust ratings went up. Once their trust ratings were sufficiently high to engage in high-value deals, the group suddenly "turned evil and cashed out." That is, they used their reputations to start auctions for high-priced items, received payment for those items, and then disappeared, leaving dozens of eBay users holding the bag.

Feedback forum

Solution?

 Feedback forums  The Value of Reputation on eBay: A Controlled Experiment (Resnick et. al. 2006) “Reputation systems seek to inform buyers about whether potential trading partners are trustworthy, and thereby to make chiseling and cheating rare and losing propositions.” →→ **incentive to conduct fair business

Other Problems of Ebay’s Reputation System

   Free Riders / Selfish users Overall ratings  Same weight on large or small transactions Sybil Attacks  Forging of multiple identities for malicious intent   To gain a disproportionately large influence  Solution: Expensive generation of Sybils Faked Transactions / Shilling  Solution: transaction verification

Shilling [2]

  Submitting fake bids Submitting fake or misleading ratings   Positive shilling  positive ratings for friends to build false reputation (collusion) Negative shilling  negative ratings for competition

’s Review Reputation System [7]

 Why do we care?

  Books are particular types of goods for which reviews are particularly powerful because they help establish the meaning of the artifacts in question Reviewer are invoked as a legitimate authority

Why Do People Write Reviews

    To share their opinion with the community To build an identity as a reviewer  To get a job as a professional book reviewer Empowerment of seeing their name and review on a Web site and take pride in their ability to ‘publish’ To legitimately item (or not) promote a certain

Problems

   Expertise: only thing required is participation Slur the competition  Attack others via posting negative reviews Self Promotion  “Reviews” from friends, paid professionals, author

Problems cont.

 Review plagiarism    To promote or support the sales of a specific item, agenda, or opinion.

To increase credibility and to build their identity.

 Socket Puppets Posting the same review multiple times for the same item, under different reviewer names.

Misuse (?) of Review Space

    Used simply for free advertisements or spamming To post links that point directly to digital copies of the music itself  an easy–to–use index of copyrighted music Promotion of political agendas Direct dialog to artist and audience  systematically discredited earlier positive reviews

Links

  Direct Dialog with Artist:  http://www.amazon.com/gp/product/B0000028SR /qid=1115574821/sr=11-1/ref=sr_11_1/104 4025964-5648766?n=5174 Promotion of political agendas:  http://www.amazon.com/gp/cdp/member reviews/AHSOTSV5VRTAH/104-4025964-5648766

Example

 One author encouraged all his friends to buy his book at a special time called ‘the Amazon hour’. This resulted in a spike in his book’s sales, and brought the book to the fourth position in the best selling books of its category. Once that has been established, the author received ‘Amazon best–selling author’ status has no time dimension.

References

[1] Ben Gross, Alessandro Acquisti, “Balances of Power on eBay: Peers or Unequals?” [2] R. Dingledine, et al.”Reputation”. John F. Kennedy School of Governement.

[3] Alla Genkina, Jean Camp. “Countermeasures: Social Networks”. Indiana University, Bloomington [4] P. Resnick, R. Zeckhauser, E. Friedman, K. Kuwabara “Reputation Systems: Facilitating Trust in Internet Interactions”. University of Michigan School of Information.

[5] Beth Cox. ”Hijacking & Fraud Plague eBay Users“. SiliconValley Internet.com. 2002.

http://siliconvalley.internet.com/news/article.php/1480591 [6] P. Massa, B. Bhattacharjee. “Using Trust in Recommender Systems: an Experimental Analysis”. University of Trento & University of Maryland [7] Shay David,Trevor Pinch, “Six degrees of reputation: The use and abuse of online review and recommendation systems” [8] Gayatri Swamynathan, Ben Y. Zhao, Kevin C. Almeroth . “Decoupling Service and Feedback Trust in a P2P Reputation System”. UCSB 2005

Six degrees of reputation

1. Level of reputation is influenced by activities that take place OUTSIDE the online recommendation system 2. Paid editors write editorial book reviews trying to influence buyers to buy a specific book 3. Expert–users (reviewers) write free–form reviews and compile best–of lists and also rank the books on a numeric scale, assigning books ‘stars’ on a 1–5 scale.

Six degrees of reputation cont.

4. Lay–users (readers) rate expert–user reviews on a binary usefulness scale (useful or not) and ‘report this’ feature to report inappropriate content 5. Some reviews are highlighted and given more visibility based on the usefulness scale and the ranking of the expert–users who wrote them. Reviews that are found to be useful by more readers, or reviews that are written by credible reviewers (i.e. those reviewers whose reviews consistently get high rankings) are displayed first.

6. At the sixth level the expert–users (reviewers) themselves are credentialed based on the amount of reviews they post and the usefulness of their reviews as evaluated by the lay–users.