We investigate experimentally whether collective choice matters for individual attitudes to ambiguity. We consider a two-urn Ellsberg experiment: one urn offers a 45% chance of winning a fixed monetary prize, the other an ambiguous chance. Participants choose either individually or in groups of...

Classical power index analysis considers the individual's ability to influence the aggregated group decision by changing its own vote, where all decisions and votes are assumed to be binary. In many practical applications we have more options than either "yes" or "no". Here we generalize three...