Hitotsubashi Institute for Advanced Study


Variable Competence and Collective Performance: Unanimity vs. Simple Majority Rule


Under the unanimity rule, a single voter may alter a decision that is unanimously accepted by all other voters. Under the simple majority rule, the impact of such a voter diminishes. This paper examines the marginal effect of competence on the collective performance – the likelihood of reaching a correct decision. It is shown that under the unanimity rule (simple majority rule), adding an incompetent voter to the group is inferior (superior) to give up an existing competent voter. The negative impact of an incompetent voter cannot (can) always be balanced by adding a Moreover, improving a single voter’s competence may have a greater effect on collective performance under the simple majority rule relative to the unanimity rule.

Report No.: HIAS-E-80
Author(s): Eyal Baharad(a)
Ruth Ben-Yashar(a)
Shmuel Nitzan(a), (b)
Affiliation: (a) Department of Economics, Bar Ilan University, Ramat Gan 52900, Israel
(b) Hitotsubashi Institute for Advanced Study, Hitotsubashi University
Issued Date: November 2018
Keywords: unanimity rule, simple majority rule, voters’ competence, collective performance