The effects of the new federal electoral map: who benefits from it?

Yesterday, Election Canada released the transposition of the 2011 votes on the new electoral map. This one adds 30 ridings to the existing 308 and will be used for the next general federal election (scheduled for 2015). The 30 new ridings are in Ontario (15), Alberta (6), BC (6) and Quebec (3) (note however that even in provinces where the total number of ridings hasn't changed, the electoral boundaries were also modified).

Using the transposition of the votes, we can see that, had the new map been in effect in 2011, the Conservatives would have won most of the new seats, increasing their MPs from 166 to 188. The NDP would only have won 6 additional ridings and the Liberals 2. Looking at these numbers, medias and journalists were quick to write headlines and commentaries such as "Tories stand to benefit from electoral map" (and similarly in French).

The main problem is that this kind of analysis is, to say the least, too short sighted. In particular, the numbers presented yesterday by Election Canada show more the effects of the electoral system than the new map. With the current system (that we should change, but this is for another time), the party who finishes first in a region/province usually wins the most seats. And the system actually rewards this party with a disproportionate share of seats (compared to the share of votes). In 2011, the Tories won 54% of the seats with only 40% of the votes. Therefore, if we increase the number of seats, the winning party will receive most of them. It doesn't show a bias or effect of the map, but rather the impact of the outdated electoral system.

The main thing to notice is that since 2011, the vote intentions have changed drastically. In particular, most of the polls of the last 6 months show the Liberals of Justin Trudeau ahead. The good fortune of the Grits is particularly visible in Ontario. Given that half of the new seats are from this province, it's quite possible the new map will actually give the Liberals an edge. This could be particularly the case given that most of the new seats are in the south of Ontario (where the population growth occured), a region usually favorable to the Liberals (people are quick to forget how dominant the Liberals had been in this province for a decade before Harper won the most seats in 2011).

I decided to run an experiment to try to establish the actual effects of the new map. Using the transposition of the votes from Election Canada, I modified the seat projections model. Then I ran my usual simulations (read the FAQ page if you are not familiar with them) on the old and new map. The starting point for both sets of simulations was the same: the averaged numbers of the two recent spolls from Ekos and Abacus. The two polls show mostly the same situation: the Liberals ahead nationwide, with the Conservatives not far behind and the NDP around 24-25%. Both polls also have the LPC first in Ontario, although by different margins. All in all, these polls are consistent with most polls of the last few months (with the lead of the Liberals slowly decreasing).

What I was interested were mostly two things: which party would increase/decrease its share of seats (with the same, constant, share of votes) and would there be an effect on the probabilities of winning the next election. The results are presented below.

CPC LPC NDP Green Bloc
old map seats 103 123 78 1 3
share of seats 33.4% 39.9% 25.3% 0.3% 1.0%
chances of winning 13% 87% 0% 0% 0%
new map seats 111 137 86 1 3
share of seats 32.8% 40.5% 25.4% 0.3% 0.9%
chances of winning 8% 92% 0% 0% 0%

As you can see, the party that is actually favored by the new map is indeed the Liberal Party of Canada, not the Conservative Party. But the impact is quite small. In term of seats, we can see that the Grits would receive the biggest increase, similarly to the fact the Conservatives were benefiting from the increased number of seats in 2011 in the transposition. The biggest effect is however on the chances of winning. Harper and his party drop from 12% chances to only 8%. As a reminder, these probabilities accont for the uncertainity due to the polls (i.e: we are not sure of the actual vote intentions) as well as the one due to the electoral system (and where the vote is).

Let's be clear here: with the same vote intentions (the current ones based on the polls), the new map increases the chances of winning for the Liberals by 5 points. If anything, it should be clear that the new map actually benefits Justin Trudeau. Why is it the case? One answer is of course in Ontario where the Liberals, currently ahead, would win most of the new seats. People are quick to point out the 6 additional seats in Alberta where the Tories have dominated for a long time. That is true, but let's not forget that 24 of the new 30 seats are in Quebec, Ontario and BC. These three provinces hardly qualify as safe lands for the Tories.

At the end of the day, what you should take from these numbers is the following:

- Who benefits from the increased number of seats is essentially a question of which party finishes first in term of votes.
- The effect is therefore mostly due to the electoral system, not the map itself.
- Even in cases where one party is almost guaranteed to win most of the new seats (like in Alberta), let's remember that the new map only corrects for the changes in demographics. In other words, Alberta deserves the added seats and if the Tories (or any party) win them, it's only because they are popular in this province. Winning seats because you are the favote option is only natural. If anything, we should be talking of the bias of the 2011 map where some provinces were under-represented at the House of Commons.

Overall, it seems to me the new map doesn't have a real effect. In particular, I don,t think we can speak of an advantage for the Tories simply because they would have won most of the new seats in 2011. The results of my simulations show relatively small effects, especially in term of seats. I'll of course re-run them if the vote intentions change drastically between now and the next election.