Reputation System

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 and collaborative filtering, 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 (Resnick et al. 2000)(Jøsang, Ismail & Boyd 2007), and often functions by making the reputation more visible.

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 or Flickr. 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.