Incentives and Efficiency in Uncertain Collaborative Environments

We consider collaborative systems where users make contributions across multiple available projects and are rewarded for their contributions in individual projects according to a local sharing of the value produced. This serves as a model of online social computing systems such as online Q&A forums and of credit sharing in scientific co-authorship settings. We show that the maximum feasible produced value can be well approximated by simple local sharing rules where users are approximately rewarded in proportion to their marginal contributions and that this holds even under incomplete information about the player's abilities and effort constraints. For natural instances we show almost 95% optimality at equilibrium. When players incur a cost for their effort, we identify a threshold phenomenon: the efficiency is a constant fraction of the optimal when the cost is strictly convex and decreases with the number of players if the cost is linear

Should Political Scientists Use the Self-Confirming Equilibrium Concept? Explaining the Choices of Cognitively Limited Actors

Many claims about political behavior are based on implicit assumptions about human reasoning. One such assumption, that political actors think in complex and similar ways when assessing strategies, is nested within widely used game theoretic equilibrium concepts. Empirical research casts doubt on the validity of these assumptions in important cases. For example, the finding that some citizens expend limited cognitive energy to social concerns runs counter to the assumption that citizens (e.g., jurors) base all decisions on complex thoughts. Similarly, evidence that some political actors (e.g., Democrats and Republicans) think about political cause-and-effect quite differently runs against the assumption that all players reason about politics in similar ways. The self-confirming equilibrium (SCE) concept provides a means for evaluating the robustness of theoretical conclusions to the introduction of a broad range of psychological assumptions. Through arguments and examples, we explain opportunities and challenges inherent in using the SCE concept. We find that the concept provides an improved foundation for more serious and constructive interactions between formal theoretic and psychology-oriented literatures.political science; equilibrium concepts; cognition; jury decision making; self-confirming equilibrium; Nash equilibrium; need for cognition; conjecture; belief