No system ticks all the boxes

If you have ever stayed awake at night worrying about the difference between the Hagenbach-Bischoff method and the Droop quota, this is the book for you. It is a treasure trove of information about electoral systems and comprehensively examines how votes get translated into seats across the democratic world.

As the Nobel-prizewinning economist Kenneth Arrow showed in the early 1950s, there is no such thing as a perfect electoral system. All systems face trade-offs between desirable objectives, and improvements in one can lead to the deterioration of another. For example, reform might make hitherto wasted votes count more effectively in influencing election outcomes, but only at a cost of making the electoral accountability of political parties more obscure.

The authors tackle the "so-what?" question very early on by asking: "Why should anyone care whether a country opts for the D'Hondt or the Sainte-Lagu method of allocating seats?" In reply to this question, they make a compelling case that electoral systems matter in a number of key ways: these methods influence the number of competitive parties in a country and the party system more generally; they change the nature of the government (whether coalition or single party); they alter the behaviour of parliamentarians and the accountability of legislatures; they influence the extent to which parliamentarians are a social cross-section of the wider communities they seek to represent; and finally, they stimulate (or suppress) electoral participation.

The book focuses particularly on two aspects: first, it examines the relationship between electoral systems and policy outcomes, a recurring theme of research in this area; second, it examines the less well-researched issue of the politics of electoral system reform. Not surprisingly, reform is highly contested, involving conflicts between different groups producing clear gainers and losers.

A key issue is to explain the political circumstances under which reform is likely to occur. As one contributor notes, there is an inverse relationship between having the will and the power to change an electoral system: when a party has the will it does not have the power, and when it has the power it does not have the will. When discussing this topic with students, I usually ask them to consider the following question: why should turkeys vote for Christmas? It is the very legislators who are likely to be losers under a reformed system who have to implement the reforms. Given this, it is not surprising that reform usually occurs when regimes change, as in the case of the transition from communism to democracy in Eastern Europe.

Richard Katz takes issue with this analysis in his chapter and tries to convince the reader that the paucity of electoral reforms has little to do with the blocking power of incumbents. He admits that there are only 14 cases of such reforms in the established democracies since 1950, but purports to find evidence that "contingent and inherent" factors such as "fashions for reform" can overcome incumbent veto powers. He even suggests, rather bizarrely, that a misspoken promise by a politician triggered the New Zealand electoral reform, which, if true, must be the biggest political gaffe in electoral history.

The major normative argument for electoral reform relates to the extent to which a system fails to translate vote shares into seat shares, and this is commonly measured by a statistic devised by one of the editors, Michael Gallagher, called the least-squares index. Interestingly enough, the 2005 general election placed Britain second from the bottom of 22 countries in the accuracy with which our system translates votes into seats in the House of Commons. This is not just a function of the first-past-the-post electoral system, however, since the result of the last UK election was, according to the index, almost four times as disproportional as the Congressional House elections of 2004, when the US has the same system as Britain.

It is noteworthy that there is a negative correlation between electoral turnout in Britain and the disproportionality of the electoral system over time. Thus a system that does an increasingly poor job in translating voter preferences into representation in the House of Commons appears to put people off voting altogether.

The missing voices in this volume are the voters themselves. There is now quite a bit of cross-national data on people's attitudes to elections and their opinions about the state of democracy in their countries. None of this is referred to in the book. That aside, this is a welcome addition to the literature on elections that provides a wealth of detail in the case studies. By the way, the Hagenbach-Bischoff method is the same as the Droop quota (except when it is used to describe a special way of implementing the D'Hondt method). So now you know.

Paul Whiteley is professor of government, Essex University, and co-director of the British Election Study.