In fact, though, such proportionality is rare, particularly in Canada with its First-Past-the-Post and multiparty systems. Calls for abolition of FPTP (or 'winner-takes-all') election systems are strongest in multiparty systems; in bipartisan political systems, the effect is more minimal.
Canada is an interesting country, in that at the federal level and across each province, a number of parties vie for office. Federally, for example, we currently have five that can be called 'major'. Yet ultimately, federally and in most provinces it ultimately comes down to two parties with a realistic chance of governing and a group of others with, at best, a chance of holding sway in minority governments. The Atlantic provinces are an interesting case in point, ranging from PEI, the most truly bipartisan part of Canada, to Nova Scotia, which is perhaps the only legitimately multipartisan area of Canada at the moment. Somewhere in the middle lies New Brunswick.
For most of New Brunswick's history, it's been genuinely bipartisan: in recent years the NDP has at best been able to get one seat - the leader's - in the Legislative Assembly. Apart from that, and with one major exception (which I'll get to), the trend has been that in a provincial election the Progressive Conservatives and the Liberals will combine for about 90% of the vote. In other words, the vast majority of people in New Brunswick see their elections on a strictly binary basis.
When this is the case, disproportionality changes in importance: when one party squeaks above fifty percent, disproportionality either doesn't really matter (is there a real difference between, say, 60% of the legislature or 70%?) or is of terrible importance (if the elections return a simple majority of votes for Party A but a simple majority of seats for Part B). While looking blandly bipartisan on the surface, New Brunswick actually has had quite an interesting electoral history:
- In both 1970 and 1974, the Progressive Conservatives got parliamentary majorities despite getting fewer votes than the Liberals, making fully eight years of majority government of questionable legitimacy.
- In 1987, a landslide 60.4% of the vote (compared to 28.6% for the PCs and 10.6% for the NDP) returned every single seat in the Assembly to the Liberal Party, leading to four years of unopposed government.
- The very next election in 1991 led to what appeared to be a complete restructuring of the electoral scene, as the Liberals got a second majority, but the upstart Confederation of Regions Party got eight seats, 21.2% of the vote and the status of Official Opposition, and both the PCs and the NDP has representation in a four-part parliament. Yet by the next election, the Liberals and the PCs were back to a combined vote of 82.5%.
I've become interested in the Gallagher Index, a tool to measure disproportionality. It gives a particular number, based on some fancy math resulting from the difference between percent of popular vote and percent of seats in the Legislative Assembly for each party.
I calculated it last night based on the numbers then posted on the CBC's website. It seems they have shifted a little bit, but at the moment I don't feel like recalculating the numbers. In any case:
- The PCs got 48.92% of the vote and 76.36% of the seats, a difference of 27.44 points.
- The Liberals got 34.45% of the vote and 23.64% of the seats, a difference of -10.81 points.
- The NDP got 10.29% of the vote and no seats, a difference of -10.29 points.
- The Greens got 4.54% of the vote and no seats, a difference of -4.54 points.
- The People's Alliance got 1.18% of the vote and no seats, a difference of -1.18 points.
- Independents got 0.62% of the vote and no seats, a difference of -0.62 points.