Reputation system
Encyclopedia
A reputation system computes and publishes reputation scores for a set of objects (e.g. service providers, services, goods or entities) within a community or domain, based on a collection of opinions that other entities hold about the objects. The opinions are typically passed as ratings to a reputation center which uses a specific reputation algorithm to dynamically compute the reputation scores based on the received ratings.

Entities in a community use reputation scores for decision making, e.g. whether or not to buy a specific service or good. An object with a high reputation score will normally attract more business than an object with a low reputation score. It is therefore in the interest of objects to have a high reputation score.

Since the collective opinion in a community determines an object's reputation score, reputation systems represent a form of collaborative sanctioning and praising. A low score represents a collaborative sanctioning of an object that the community perceives as having or providing low quality. Similarly, a high score represents a collaborative praising of an object that the community perceives as having or providing high quality. Reputation scores change dynamically as a function of incoming ratings. A high score can quickly be lost if rating entities start providing negative ratings. Similarly, it is possible for an object with a low score to recover and regain a high score.

Reputation systems are related to recommender systems
Recommendation system
Recommender systems, recommendation systems, recommendation engines, recommendation frameworks, recommendation platforms or simply recommender form or work from a specific type of information filtering system technique that attempts to recommend information items Recommender systems, recommendation...

 and collaborative filtering
Collaborative filtering
Collaborative filtering is the process of filtering for information or patterns using techniques involving collaboration among multiple agents, viewpoints, data sources, etc. Applications of collaborative filtering typically involve very large data sets...

, but with the difference that reputation systems produce scores based on explicit ratings from the community, whereas recommender systems use some external set of entities and events (such as the purchase of books, movies, or music) to generate marketing recommendations to users. The role of reputation systems is to facilitate trust , and often functions by making the reputation
Reputation
Reputation of a social entity is an opinion about that entity, typically a result of social evaluation on a set of criteria...

 more visible
Social translucence
Social translucence is a term that was proposed by Thomas Erickson and Wendy A. Kellogg to refer to "design digital systems that support coherent behavior by making participants and their activities visible to one another"....

.

Reputation systems are often useful in large online communities in which users may frequently have the opportunity to interact with users with whom they have no prior experience or in communities where user generated content is posted like YouTube
YouTube
YouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....

 or Flickr
Flickr
Flickr is an image hosting and video hosting website, web services suite, and online community that was created by Ludicorp in 2004 and acquired by Yahoo! in 2005. In addition to being a popular website for users to share and embed personal photographs, the service is widely used by bloggers to...

. In such a situation, it is often helpful to base the decision whether or not to interact with that user on the prior experiences of other users.

Reputation systems may also be coupled with an incentive system to reward good behavior and punish bad behavior. For instance, users with high reputation may be granted special privileges, whereas users with low or unestablished reputation may have limited privileges.

Types of reputation systems

A simple reputation system, employed by eBay
EBay
eBay Inc. is an American internet consumer-to-consumer corporation that manages eBay.com, an online auction and shopping website in which people and businesses buy and sell a broad variety of goods and services worldwide...

, is to record a rating (either positive, negative, or neutral) after each pair of users conducts a transaction. A user's reputation comprises the count of positive and negative transactions in that user's history.

More sophisticated algorithms scale an individual entity's contribution to other nodes' reputations by that entity's own reputation. PageRank
PageRank
PageRank is a link analysis algorithm, named after Larry Page and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set...

 is such a system, used for ranking web pages based on the link structure of the web. In PageRank, each web page's contribution to another page is proportional to its own pagerank, and inversely proportional to its number of outlinks.

Reputation systems are also emerging which provide a unified, and in many cases objective, appraisal of the impact to reputation of a particular news item, story, blog or online posting. The systems also utilize complex algorithms to firstly capture the data in question but then rank and score the item as to whether it improves or degrades the reputation of the individual, company or brand in question.

Online reputation systems

Howard Rheingold
Howard Rheingold
-See also:* Collective intelligence* Information society* The WELL* Virtual community-External links:***** at TED conference** a 48MB Quicktime movie, hosted by the Internet Archive...

 states that online reputation systems are 'computer-based technologies that make it possible to manipulate in new and powerful ways an old and essential human trait'. Rheingold inclines that these systems arose as a result of the need for Internet users to gain trust in the individuals they transact with online. The innate trait he makes note of in humans is that functions of society such as gossip 'keeps us up to date on who to trust, who other people trust, who is important, and who decides who is important'. Internet sites such as eBay
EBay
eBay Inc. is an American internet consumer-to-consumer corporation that manages eBay.com, an online auction and shopping website in which people and businesses buy and sell a broad variety of goods and services worldwide...

 and Amazon
Amazon.com
Amazon.com, Inc. is a multinational electronic commerce company headquartered in Seattle, Washington, United States. It is the world's largest online retailer. Amazon has separate websites for the following countries: United States, Canada, United Kingdom, Germany, France, Italy, Spain, Japan, and...

 he argues seek to service this consumer trait and are 'built around the contributions of millions of customers, enhanced by reputation systems that police the quality of the content and transactions exchanged through the site'.

Other examples of practical applications

  • Search: web (see PageRank
    PageRank
    PageRank is a link analysis algorithm, named after Larry Page and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set...

    ), blogs (see blog search engines)
  • eCommerce: eBay
    EBay
    eBay Inc. is an American internet consumer-to-consumer corporation that manages eBay.com, an online auction and shopping website in which people and businesses buy and sell a broad variety of goods and services worldwide...

    , Epinions
    Epinions
    Epinions.com is a general consumer review site that was established in 1999. Epinions was acquired by Shopping.com in 2003, which in turn was acquired by Ebay in 2005...

    , Bizrate
  • Social news: Slashdot
    Slashdot
    Slashdot is a technology-related news website owned by Geeknet, Inc. The site, which bills itself as "News for Nerds. Stuff that Matters", features user-submitted and ‑evaluated current affairs news stories about science- and technology-related topics. Each story has a comments section...

    , Reddit
    Reddit
    reddit is a social news website where the registered users submit content, in the form of either a link or a text "self" post. Other users then vote the submission "up" or "down," which is used to rank the post and determine its position on the site's pages and front page.Reddit was originally...

    , Digg
    Digg
    Digg is a social news website. Prior to Digg v4, its cornerstone function consisted of letting people vote stories up or down, called digging and burying, respectively. Digg's popularity prompted the creation of copycat social networking sites with story submission and voting systems...

  • Device Reputation System: iovation Inc.; used by major companies like UPS.
  • Programming communities: Advogato
    Advogato
    Advogato is an online community and social networking site dedicated to free software development, and was created by Raph Levien. It describes itself as "the free software developer's advocate." Advogato was an early pioneer of blogs, formerly known as "online diaries", and one of the earliest...

    , freelance marketplace
    Freelance marketplace
    Freelance marketplaces are websites that match buyers and sellers of services provided via the internet. Service providers, or sellers, create a profile where they include a description of the services which they offer, examples of their work and in some cases information about their rates...

    s, Stack Overflow
    Stack overflow
    In software, a stack overflow occurs when too much memory is used on the call stack. The call stack contains a limited amount of memory, often determined at the start of the program. The size of the call stack depends on many factors, including the programming language, machine architecture,...

  • Internet Security: TrustedSource
    TrustedSource
    TrustedSource is an Internet reputation system originally developed by CipherTrust and now owned by McAfee. It provides reputation scores for Internet identities, such as IP addresses, URLs, domains, and email/web content....

  • Email: anti-spam techniques, reputation lookup (RapLeaf
    Rapleaf
    Rapleaf is a Web 2.0 start-up company based in San Francisco, California founded by Auren Hoffman and Manish Shah. Acting primarily a B2B firm, Rapleaf's consumer information technology helps businesses understand their customers so they can personalize experiences in real time, segment customers,...

    )
  • Peer-to-peer: identifying trusted nodes
  • Personal Reputation: PersonRatings.com
    PersonRatings.com
    PersonRatings.com was a website where users could rate and review individuals, regardless of profession. The site allowed users to read about and rate others on a range of qualities, including trustworthiness. The site purported to be a "Yelp about people" . Anyone was free to log on and...

    , CouchSurfing
    CouchSurfing
    CouchSurfing International Inc. is a corporation based in San Francisco that offer its users hospitality exchange and social networking services. It is a for-profit private corporation, planning to go public. With more than 3 million profiles in 246 countries and territories, CouchSurfing has an...

     (for travelers)
  • Non Governmental organizations (NGOs): www.GreatNonProfits.org, GlobalGiving
    GlobalGiving
    GlobalGiving is an online marketplace that connects donors with grassroots projects in the developing world. Potential donors can browse and select from a wide offering of projects, organized by geography or by themes such as health care, the environment, and education...

  • Professional reputation of translators and translation outsourcers: BlueBoard at ProZ.com
    ProZ.com
    ProZ.com is a business-related social networking site for translation. Founded in 1999, it is mainly used for professional networking. Several important language industry companies advertise their products there...

    , HFS at Translatorscafe.com
  • All purpose reputation system: Yelp, Inc., Customer Lobby
    Customer Lobby
    Customer Lobby is a web-based client to proactively invite end-customers for reviews, verify their authenticity before publishing, and correspond with consumers to manage negative reviews...


Attacks on reputation systems

Reputation systems are in general vulnerable to attacks, and many types of attacks are possible . A typical example is the so-called Sybil attack
Sybil attack
The Sybil attack in computer security is an attack wherein a reputation system is subverted by forging identities in peer-to-peer networks. It is named after the subject of the book Sybil, a fictional case study of a woman with multiple personality disorder...

 where an attacker subverts the reputation system by creating a large number of pseudonymous
Pseudonymity
Pseudonymity is a word derived from pseudonym, meaning 'false name', and anonymity, meaning unknown or undeclared source, describing a state of disguised identity. The pseudonym identifies a holder, that is, one or more human beings who possess but do not disclose their true names...

 entities, and using them to gain a disproportionately large influence . A reputation system's vulnerability to a Sybil attack depends on how cheaply Sybils can be generated, the degree to which the reputation system accepts input from entities that do not have a chain of trust linking them to a trusted entity, and whether the reputation system treats all entities identically. It is named after the subject of the book Sybil
Sybil (book)
Sybil is a 1973 book by Flora Rheta Schreiber about the treatment of Sybil Dorsett for dissociative identity disorder by her psychoanalyst, Cornelia B...

, a case study of a woman with multiple personality disorder
Dissociative identity disorder
Dissociative identity disorder is a psychiatric diagnosis and describes a condition in which a person displays multiple distinct identities , each with its own pattern of perceiving and interacting with the environment....

.

See also

  • Reputation management
    Reputation management
    Reputation management , also known as directory management, is the process of tracking an entity's actions and other entities' opinions about those actions; reporting on those actions and opinions; and reacting to that report creating a feedback loop. All entities involved are generally people, but...

  • Collaborative filtering
    Collaborative filtering
    Collaborative filtering is the process of filtering for information or patterns using techniques involving collaboration among multiple agents, viewpoints, data sources, etc. Applications of collaborative filtering typically involve very large data sets...

  • Web of trust
    Web of trust
    In cryptography, a web of trust is a concept used in PGP, GnuPG, and other OpenPGP-compatible systems to establish the authenticity of the binding between a public key and its owner. Its decentralized trust model is an alternative to the centralized trust model of a public key infrastructure ,...

  • Trust metric
    Trust metric
    In psychology and sociology, a trust metric is a measurement of the degree to which one social actor trusts another social actor...

  • Online participation
    Online participation
    Several motivations lead people to contribute to virtual communities. Various online media , are becoming ever greater knowledge-sharing resources. Many of these communities are highly cooperative and establish their own unique culture...

  • Subjective logic
    Subjective logic
    Subjective logic is a type of probabilistic logic that explicitly takes uncertainty and belief ownership into account. In general, subjective logic is suitable for modeling and analysing situations involving uncertainty and incomplete knowledge...

  • Social translucence
    Social translucence
    Social translucence is a term that was proposed by Thomas Erickson and Wendy A. Kellogg to refer to "design digital systems that support coherent behavior by making participants and their activities visible to one another"....

  • Honor system
    Honor system
    An honor system or honesty system is a philosophical way of running a variety of endeavors based on trust, honor, and honesty. Something that operates under the rule of the "honor system" is usually something that does not have strictly enforced rules governing its principles...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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