CouchSurfing

CouchSurfing is a hospitality exchange website. There are several ways that people can indicate that they're trusting each other.

Trust systems

 * References
 * extremely negative, negative, neutral, positive, extremely positive


 * Friendship links
 * 1 to 7
 * includes some information that is not shown on profiles


 * Vouches
 * yes or no, (almost) not possible to undo a vouch


 * Verification
 * this does two things:
 * verifies that the name on the profile is the same as the member's name on their credit card
 * verified that that mailing address is the same on their profile
 * once verified members cannot change this information without starting the process over

Trust metric task: predict who should you contact
A trust metric can be used to predict which users is better to be contacted for the active user.

Example: Mary is going to Paris, the system (using a trust metric) could suggest her which users in Paris she is more likely to enjoy and to contact her.

Negative reference retaliation

 * 1) Bob is staying at Alice's home. Bob seriously misbehaves.
 * 2) Alice leaves Bob a bad reference.
 * 3) Bob leaves a bad reference for Alice.

Q: Who to trust?

This is a very tricky situation that probably requires human intervention and a good dose of mutual understanding and talking. Negative feedback retaliation is reported to happen on Ebay.

Research
Paula Bialski has done research on trust in the couchsurfing network.