Recently, we had a federal election here in Canada, and many people noticed that when all was said and done, the distribution of seats in the House of Commons didn’t very closely match the distribution of votes that each party received.  There is a good reason for this, and it has to do with the voting system we use here in Canada, a system known as “First Past the Post” or “Single Member Plurality”.  Given the recent election here in Canada, as well as the fact that people in the UK recently engaged in a referendum about whether they should change their voting system (they opted not to), we thought our readers might be interested in a brief overview of how our system works, what some of the alternatives are, and the history of alternative voting systems in Canada.
Single Member Plurality
Here in Canada, we use a system based on the Westminster parliamentary system found in the United Kingdom.  The Single Member Plurality system (also known as the “winner take all” system) has the advantage of being very easy to understand.  Basically, Canada is divided up into 308 geographical areas (known as “ridings”), and voters in those areas cast a ballot for the candidate that they feel would best represent them.  The candidate in each riding who garners the most votes is declared the winner and becomes a Member of Parliament.  There are a number of advantages to this system, not the least of which is that it is very simple.  People cast one vote, and that vote is directly accounted to a single candidate.  Moreover, it allows people to vote for a person who is explicitly responsible for the area that they live in, giving a sense of direct representation.
There are, however, some downsides to this system.  Because a candidate only has to get more votes than every other candidate to win, the winner doesn’t necessarily have to get the support of the majority of the voters in their riding.  Here is an example from the 2011 election:

Notice that Conservative candidate John Baird received the support of less than half of the voters in the riding, but because he received a plurality of votes (more votes than anyone else) he was declared the winner and will represent all of the voters in the House of Commons.
While this might seem somewhat unequal on a local level, the difference is even more pronounced if you look at the results across the entire country.  In our political system, the party that wins the largest number of seats is generally the party that forms the government, especially if that party wins a majority of the seats, as the Conservative Party did in 2011.  But, just as a candidate can win a riding without the support of the majority of voters, so too can a party win a majority of the seats in the House of Commons without the support of the majority of Canadians.  In the 2011 federal election, the popular vote each party received is as follows:

Green Party: 3.9%
Conservative Party: 39.6%
Liberal Party: 18.9%
NDP: 30.6%
Bloc Quebecois: 6.0%

But the actual percentage of seats that each party won was very different:

Green Party: 0.3%
Conservative Party: 54.2%
Liberal Party: 11.0%
NDP: 33.1%
Bloc Quebecois: 1.3%

In fact, if the seats in the House of Commons were distributed proportionally to the votes that each party received, the House would look very different:

Image by Bryan Beca. Click for full size

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