The Economist in its "World in 2005" report ranked the world's countries on a quality-of-life index. Ireland was number one, with a brand of proportional voting much like one of the two we advocate for congressional elections in this country (choice voting in relatively small multi-member districts that we call superdistricts). And of the top ten, every country uses some form of proportional voting.

1. Ireland - choice voting (STV) 2. Switzerland - list proportional voting 3. Norway - list proportional voting in superdistricts 4. Luxembourg - list proportional voting in 15-member superdistricts 5. Sweden - proportional voting with some superdistricts, some nationally elected seats 6. Australia - choice voting (STV) for the Senate 7. Iceland - list proportional voting 8. Italy - list proportional voting with a bonus for the winning pre-election coalition (partial proportional voting, partial winner-take-all at time of indexing) 9. Denmark - proportional voting with some superdistricts, some nationally elected seats 10. Spain - list proportional voting in superdistricts coextensive with provinces

(For the uninitiated, "list proportional voting" is when the voter chooses a party, not a candidate. Choice voting, or STV, is where the voter ranks his or her individual choices by name. One is a party-centric system, the other candidate-centric. In practice, the party/candidate distinction is a continuum, with all sorts of blends in between.)

What does the index take into consideration? It's important to know, because (1) indices differ in their derivation and (2) some criteria here may give us insight into potential causality behind the correlation.

So ours takes a new approach. We use life-satisfaction surveys (assembling the average scores for 74 countries) as a starting point for weighting the various factors that determine quality of life. A regression analysis suggests that as many as nine indicators have a significant influence, and can be turned into an equation explaining more than 80% of the variation in countries" life-satisfaction scores. The main factor is income, but other things are also important: health, freedom, unemployment, family life, climate, political stability and security, gender equality, and family and community life (emphasis mine). We feed the factors into the equation, measuring them using forecasts for 2005 where possible (in four cases) and latest data for slower-changing indicators, such as family life and political freedom. The resulting score, on a scale of one to ten, gives the quality-of-life index. A full explanation of the methodology and a full country ranking are available to download here.

Low unemployment. Freedom. Political stability. Gender equality (after the last election, only 13% of U.S. House members are women - though seen as a major gain, we're still well behind the PR democracies). All are qualities we might associate with political inclusion, broadly speaking. That's the goal of proportional voting systems: to make our legislative bodies more closely mirror our population.