I’m working on a project and I’ve run into an issue: how do I state the vote percentages for winning candidates in a multi-member constituency, when each voter only has one vote, in a first-three-past-the-post system?
It’s real easy, obviously, when you have a single-member constituency. You take the vote the candidate got, divide by the total votes cast, multiply by 100, and there’s your percentage.
But what happens if you’ve got a constituency that elects three members, but each voter only gets to cast one vote? You might get something like this:
Mr Able: 10,000
Ms Baker: 9,000
Mr Cook: 8,000
Ms Dumont: 5,000
Mr Edwards: 4,000
Ms Fair: 3,000
Mr Goulet: 2,500
Ms Houle: 2,000
Mr. Innis: 1,500
Ms. Jay: 1,000
Total votes cast: 46,000
If this were a single-member consitituency, it would be completely fair to say that Able’s getting elected with only 21.7% of the vote.
But it’s a three member constituency. If you just take a percentage, Mr Able looks like he’s getting elected by 21.7%, but that’s not really accurate. Because it’s a single-vote system that elects three candidates, just running the total votes seems to me to undercut the level of support he got.
Collectively, the three winners pulled in (Able, Baker and Cook) pulled in 58.7% of the votes cast. That seems a more accurate estimate of the level of their support, stating what’s needed to get elected. But I don’t think that’s really a good way to try to express the percentage, either.