What to do about Election Inversions under Proportional Representation?

Abstract

An election inversion occurs when a party, or coalition of parties, wins more seats in the legislature than another party, or coalition of parties, despite the fact that the other party, or coalition of parties, won a larger number of votes cast in an election. It is well known that such inversions can and do occur under the kind of ‘majoritarian’ electoral systems commonly used in English-speaking countries. It has recently been observed that such inversions not only can and do occur also under party-list proportional representation (PR) systems, but also that they are unavoidable due to the ‘whole number problem’. This finding raises the question of whether and how the problem of election inversions under PR systems might be solved or mitigated. We consider a number of options and point out their relative advantages and disadvantages.