Trust metric

In psychology and sociology, a trust metric is a measure of how a member of a group is trusted by the other members. Trust metrics may be abstracted in a manner that can be implemented on computers, making them of interest for the study and engineering of virtual communities, such as Friendster and LiveJournal. Attack resistance is an important property of trust metrics which reflects their ability not to be overly influenced by agents who try to manipulate the trust metric and who participate in bad faith (i.e. who aim to abuse the presumption of trust).

The first commercial forms of trust metrics in computer software were in applications like eBay's Feedback Rating. Slashdot introduced its notion of "karma", earned for activities perceived to promote group effectiveness, an approach that has been very influential in later virtual communities.

Another formal trust metric and trust model is that of subjective logic which in addition to trust levels includes the ability to express ownership (subjectivity) and degrees of uncertainty. A fundamental property of this model is that trust is diluted, i.e. becomes more uncertain, through transitivityA. Jøsang, R. Hayward, S. Pope. Trust Network Analysis with Subjective Logic. Proceedings of the Australasian Computer Science Conference (ACSC'06), Hobart, January 2006. [http://sky.fit.qut.edu.au/~josang/papers/JHP2006-ACSC.pdf PDF] ] . This metric is used in some online communities like e.g. Rummble.com.

Recently, researchers have shown that trust transitivity does not always hold and, consequently, have proposed new trust metrics [D. Quercia, S. Hailes, L. Capra. [http://www.cs.ucl.ac.uk/staff/d.quercia/publications/quercia07lightweight.pdf Lightweight Distributed Trust Propagation] . ICDM'07. ] .

The free software developer resource Advogato is based on a novel approach to attack resistant trust metrics of Raph Levien. Levien observed that Google's PageRank algorithm can be understood to be an attack resistant trust metric rather similar to that behind Advogato. Despite the trust metric a widely-known Internet psychopath has gained posting privileges to the front page [ [http://www.advogato.org/article/910.html Advogato: Mentifex on AI ethical decisions of life and death in artificial intelligence ] ] of Advogato, illustrating just how complex the problem of trust is.

[http://trustlet.org/wiki Trust Metrics Wiki] is a Wiki whose goal is to review, understand, code and compare on same data all the trust metrics proposed so far.

Trust metrics are closely related to reputation systems.

ee also

*Trust (sociology)
*Trustworthiness
*Web of trust
*Subjective logic

References

External links

* [http://www.trustlet.org/wiki/Trust_Metrics_Evaluation_project Trust Metrics Evaluation Project] of Paolo Massa. The [http://www.trustlet.org/wiki/AnalyzedTrustMetrics Analyzed Trust Metrics page] provides an extensive bibliography of work on the theory and implementation of trust metrics.
* [http://www.trustcomp.org Trustcomp.org] is an online community of more than 150 academic and industrial members who research computational trust management and online reputation. There is also a [http://groups.yahoo.com/group/trustcomp/ mailing list] .
* [http://www.unik.no/people/josang/sl/ Online demonstrations] of subjective logic.
*Raph Levien, 2000. [http://www.advogato.org/trust-metric.html Advogato's trust metric] . Electronic manuscript.
*Raph Levien, 2002. [http://www.levien.com/free/tmetric-HOWTO.html Attack Resistant Trust Metric Metadata HOWTO] . Electronic manuscript.