With the Canadian 2011 election at a close, I thought I’d take a minute to estimate the Condorcet winners per riding. The data’s available in preliminary form through Elections Canada. Let’s look at Scarborough Centre as an example for how FPTP voting fails to elect a representative candidate
| Riding results for Scarborough Centre | |
|---|---|
| Liberal | 12075 (32.0%) |
| NDP | 11273 (29.9%) |
| Conservative | 13401 (35.5%) |
| Green | 994 (2.6%) |
Using the CBC vote compass, we can approximate how these voters might have ranked each candidate if given the option for a more expressive ballot.
| Estimated preference ballots for Scarborough Centre | |
|---|---|
| 3945 | NDP, Green, Liberal |
| 3945 | NDP, Liberal / Green |
| 3381 | NDP, Liberal, Green |
| 994 | Green, NDP, Liberal |
| 10867 | Liberal, NDP / Green |
| 1207 | Liberal, Conservative |
| 13401 | Conservative, Liberal |
Given these preferences (which I admit are a wild estimate; people vote tactically concealing their true preferences), the Condorcet winner would be the Liberal Party’s candidate. Indeed, the national breakdown would have produced results like so (full estimate attached):
| Seats won per party under the Schulze Method | |
|---|---|
| Liberal | 111 (up 8 seats from 2008) |
| Conservative | 110 (down 33 seats) |
| NDP | 51 (up 22 seats) |
| Bloc | 35 (down 14 seats) |
| Green | 1 (up 1 seat) |
For the curious, the code used to generate the above is attached.