American Economic Journal:
Microeconomics
ISSN 1945-7669 (Print) | ISSN 1945-7685 (Online)
A Random Dictator Is All You Need
American Economic Journal: Microeconomics
vol. 17,
no. 1, February 2025
(pp. 66–96)
Abstract
We study information aggregation with a decision-maker aggregating binary recommendations from symmetric agents. Each agent's recommendation depends on her private information about a hidden state. While the decision-maker knows the prior distribution over states and the marginal distribution of each agent's recommendation, the recommendations are adversarially correlated. The decision-maker's goal is choosing a robustly optimal aggregation rule. We prove that for a large number of agents for the three standard robustness paradigms (maximin, regret, and approximation ratio), the unique optimal aggregation rule is "random dictator." We further characterize the minimal regret for any number of agents through concavification.Citation
Arieli, Itai, Yakov Babichenko, Inbal Talgam-Cohen, and Konstantin Zabarnyi. 2025. "A Random Dictator Is All You Need." American Economic Journal: Microeconomics 17 (1): 66–96. DOI: 10.1257/mic.20230255Additional Materials
JEL Classification
- D81 Criteria for Decision-Making under Risk and Uncertainty
- D82 Asymmetric and Private Information; Mechanism Design
- D83 Search; Learning; Information and Knowledge; Communication; Belief; Unawareness
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