Jain, Shaili, Yiling Chen, and David C. Parkes. "Designing incentives for online question and answer forums." Proceedings of the 10th ACM conference on Electronic commerce. 2009.

This paper presents a game-theoretic model of online question and answer forums, focusing on factual questions where user responses accumulate while a question remains open. Users each possess unique information and choose when to report it. The asker prefers timely responses and stops when satisfied with the cumulative information. The study examines two scenarios: complements, where each new piece of information adds more value, and substitutes, where each adds less value. Using a best-answer scoring rule, effective for substitutes as seen in Yahoo! Answers, it achieves an equilibrium with immediate responses. However, for complements, this rule results in delayed responses. The paper demonstrates that approval-voting and proportional-share scoring rules can achieve efficient equilibrium for complements by incentivizing early and final responses.