Professor of Decision Sciences
This project reconciles historically distinct paradigms at the interface between individual and social choice, as well as rational and behavioral decision theory.The authors combine a utility-maximizing prescriptive rule for “sophisticated approval voting” with the “ignorance prior” heuristic from behavioral decision research, and two types of “plurality heuristics” to model approval voting behavior. When using a “sincere plurality heuristic,” voters simplify their decision process by voting for their single favorite candidate. When using a “strategic plurality heuristic,” voters strategically focus their attention on the two front runners and vote for their preferred candidate among these two.Using a hierarchy of Thurstonian random utility models, the authors implement these different decision rules and test them statistically on seven real world approval voting elections. The authors cross-validate our key findings via a psychological internet experiment. Although substantially many voters used the plurality heuristic in the real elections, they did so sincerely, not strategically.Moreover, even though Thurstonian models do not force such agreement, the authors find, in contrast to common wisdom about social choice rules, that the sincere social orders by Condorcet, Borda, Plurality, and Approval Voting are identical in all seven elections and in the internet experiment.