Randomized decision rules in voting games: a model for strict proportional power

Abstract

The concept of strict proportional power is introduced, as a means of formalizing a desire to avoid discrepancy between the seat distribution in a voting body and the actual voting power in that body, as measured by power indices in common use. Proportionality is obtained through use of a randomized decision rule (majority rule). Some technical problems which arise are discussed in terms of simplex geometry. Practical implications and problems in connection with randomized decision rules are indicated.