C-index: trust depth, trust breadth, and a collective trust measurement

Many computational trust models measure collective trust or reputation by the total number or the percentage of (pure) positive feedback a collaborator received from a community. Such measurement usually failed to reflect on how deep a trust is (i.e., how many repeated/re-tested trustworthy collaborations a collaborator has had with another) and also how widely a trust is distributed across a community (i.e. how many trustworthy collaboration occurred with different collaborators). In this work, we have defined Trust Depth (TD), Trust Breadth (TB) to measure these two aspects and proposed a C-Index to measure them in one number. Scenarios are provided to show how the C-index might be used for identifying and selecting collaborative partners.