Designing Incentives for Online Question and Answer Forums

Anyone who has posted questions to online forums like LinkedIn and Yahoo! Answers could be interested in this paper: http://www.eecs.harvard.edu/~shailij/papers/qa-ec.pdf

Title: Designing Incentives for Online Question and Answer Forums

Authors: Shaili Jain

Chen, Yiling

Parkes, David C.

ID: http://nrs.harvard.edu/urn-3:HUL.InstRepos:4340771

Shaili Jain

School of Engineering and Applied Sciences

Harvard University

Cambridge, MA 02138 USA

shailij@eecs.harvard.edu

Yiling Chen

School of Engineering and Applied Sciences

Harvard University

Cambridge, MA 02138 USA

yiling@eecs.harvard.edu

David C. Parkes

School of Engineering and Applied Sciences

Harvard University

Cambridge, MA 02138 USA

parkes@eecs.harvard.edu

ABSTRACT

In this paper, we provide a simple game-theoretic model of an online question and answer forum. We focus on factual questions in which user responses aggregate while a question remains open. Each user has a unique piece of information and can decide when to report this information. The asker prefers to receive information sooner rather than later, and will stop the process when satisfied with the cumulative value of the posted information. We consider two distinct cases: a complements case, in which each successive piece of information is worth more to the asker than the previous one; and a substitutes case, in which each successive piece of information is worth less than the previous one. A best-answer scoring rule is adopted to model Yahoo! Answers, and is effective for substitutes information, where it

isolates an equilibrium in which all users respond in the first round. But we find that this rule is ineffective for complements information, isolating instead an equilibrium in which all users respond in the final round. In addressing this, we demonstrate that an approval-voting scoring rule and a proportional-share scoring rule can enable the most efficient equilibrium with complements information, under certain conditions, by providing incentives for early respon-

ders as well as the user who submits the final answer.