Sunday, April 24, 2011

GTA Adjustment To Be Phased In

Update: I mixed up "rest of Ontario" and "Ontario as a whole" originally. The post is now fixed, and the effect is even bigger!

I've looked back at EKOS polling, which breaks out large metropolitan areas, since the start of the campaign. There are now over 1,200 data points from the GTA, so we can say something meaningful about the swing there relative to the swing in the rest of Ontario by pooling those numbers.

The GTA is a region that the Liberals carried by 8-10% in 2008 (I don't know the exact number since riding boundaries don't match neatly with GTA boundaries). That's roughly 14-15% better than the 5.4% loss they suffered province-wide.

In the six EKOS polls to date, the GTA is only about 4-5% more favourable (actually, less unfavourable) to the Liberals than Ontario as a whole, a full 10 points less than in 2008. (Forum's latest poll actually finds the GTA 4% more favourable to the Conservatives. The COMPAS poll had the Tories leading by 17% in Ontario, by >15% in the 905, but the Liberals ahead in the 416, meaning the the GTA as a whole might be 10% more favourable to the Grits. These are the only two other GTA breakdowns I came across, and they pretty much cancel each other out.)

What does this mean? I now have the Conservative Ontario lead 3.3% higher than in 2008. If EKOS is right about the relation between the GTA and the province as a whole, we actually have, roughly, a 4.4% reduction in the Tory lead in the rest of Ontario, and a 13.3% reduction to the Liberal lead in the GTA (this makes it negative, so the Tories are now ahead).

If I fully introduce the above adjustment, the Liberals would regain four seats:
- Guelph
- Kitchener--Waterloo
- Kitchener Centre
- London West.
But the Tories would add a whopping 11 GTA seats:
- Mississauga South
- Eglinton--Lawrence
- York Centre
- Don Valley West
- Ajax--Pickering
- Bramalea--Gore--Malton
- Mississauga--Streetsville
- Richmond Hill
- Etobicoke Centre
- Etobicoke--Lakeshore (not including a leader's effect)
- Scarborough Southwest.
That's a net gain of 7 for the Conservatives, enough to deliver a majority.

Now, a sample of 1,214 since the start of the campaign pales in comparison to the sample of around 6,000 we have for Ontario as a whole just in polls released this past week. The margin of error for the Conservative-Liberal gap for a sample of 1,214 is around 5%, so there is significant uncertainty regarding the size of the GTA effect. One has to be skeptical that the GTA is indeed breaking 17.7% differently from the rest of the province - that's a huge deviation for such a large region. I am hoping for pollsters to conduct polls with bigger samples in the last week, in which case more of them might release GTA numbers.

For now, I will not yet incorporate a GTA adjustment in the headline projection. When tomorrow's EKOS update comes out, which will give us another couple of hundred observations, I will start phasing it in. Whether I end up with a full or a partial adjustment depends on whether other pollsters become more forthcoming with their GTA data.

The upshot is this: as I've said in a previous post, just before the NDP surge, the GTA carries the key to a Conservative majority. The NDP is not a factor in that region, except in a few Central Toronto ridings. The Conservatives' chance of getting a majority increases significantly if the orange wave reaches suburban Toronto. If I were Jack Layton, I would avoid Ontario, particularly Toronto, for the rest of the campaign, instead spending my time in Québec, Saskatchewan and BC.

2 comments:

Bryan Breguet said...

carefull, more regional effects like this and you'll end up having an econometrics model like me lol

Interesting stuff, will check it out.

Election Watcher said...

Ugh, I hate programming. It may yet come to that... for the next election (which will be 4 years from now if current trends continue).