Online platforms are prone to abuse and manipulations from strategic parties. For example, social media and review websites suffer from sentiment manipulations, manifested in the form of opinion spam and fake reviews. The consequence of such manipulations is the deterioration of information...

Social media platforms such as Facebook show ads with popularity or general endorsement signals such as “likes”. Additionally, these ads can display social endorsement from friends (i.e., friends’ “likes”). This paper examines the effectiveness of displaying these different signals on...

Numerous online information systems (e.g., question and answer (Q&A) forums, citizen science communities, and review websites) rely heavily on volunteer contributions. Managers have used monetary incentives to induce individuals to increase their contribution level. However, monetary incentives...