Estimating the Elizabeth May effect

Elizabeth May is a puzzle for me. In 2008, she had an unique deal with Stephane Dion in that he agreed not to run any liberal candidate versus her. Yet, where did she decide to run? In the riding of Peter McKay! While she did get a pretty decent score of 32%, it wasn't enough to win and quite honestly, there was no way she would win this riding. In 2006, the Green party only got 1.59% in this riding! So why would she choose to run there? I understand this is where she lives, but still, the Green party is at the point where having an elected MP matters more than that.

So you would think May learned from her mistake and would run in a riding that she can win. But no, instead of running in Ontario where the Green did pretty good in two ridings (Guelph at 21% and Bruce-Grey at 27%), she decided to go to BC and run on Vancouver island in the riding of Saanich-Gulf-Island, a riding where the Green party only got 10.46% of the votes, well behind the Tories and the Liberals.

But can she win this riding? After all, it is clear there is a May effect. But how big is this effect? Let's estimate it using the results of 2008 and the by-election of London North/Centrer where she ran in 2006 and got a surprising 26%.

According to my estimates, in 2008, the Green party was in Central-Nova 29-points above what it should have been! Of course, this is the combine effect of Elizabeth May running AND having no Liberal candidate. Surprisingly, using the same estimation, I find that the NDP was down 15-points in this riding, while the Tories were up 8-points. Again, see those numbers as what would have happened if May wasn't the candidate and the Liberals had a candidate. It's interesting to see that some NDP voters decided to switch in order to give the Green party a chance. It isn't completely surprising given that a lot of NDP voters have the Green as second choice. It's also worth noting the little boost that CPC got. I'm guessing some Liberals voters were upset with the deal and switch to the Tories. As for the Liberals, if they had ran a candidate, I estimate they would have got 21%. So without May and with a liberal candidate, the results would have been:

CPC: 38%
LPC: 21%
NDP: 35%
Green: 3%

Instead of respectively 47%, 0%, 20% and 32%. Note how the maths sum up: the 21% of the Liberals were split into +8 for the CPC and +13 for the Green. Therefore, May got 13+15=28 points more than if it was a regular Green candidate.

So what about the May effect in the by-election in 2006? In the 2006 general election, the Green party got 5.49%. Then, during the by-election, May got 26%! So, at the end, it seems Elizabeth May does benefit of a huge boost in term of votes whenever she runs in a riding. Quantitatively, I would say she can get a jump as high as 20-points. Mostly at the expense of the NDP. Indeed, the Liberals were barely affected in the by-election. In both cases, I would say the May effect was: 5-8-points taken from the Liberals, 10-15-points taken from the NDP. (yes she got around 13-points from the Liberals in 2008, but there was no candidate. It's not the same as having liberal voters deciding to switch simply because it was Elizabeth May).

So let's be generous and give May a 20-points boost, taken at 1/3 from the Liberals and 2/3 from the NDP. Does it allow her to win her seat in BC? Using the latest Ekos poll who puts the Green as high as 19.7% in BC, we have the following projections for Saanich-Gulf-Island:

CPC: 36%
LPC: 42%
NDP: 0.1%
Green: 21.5%

Let's add the May effect. One problem is that this riding has already a low percentage for the NDP, so not so much votes to take from them! At the end, May would need to steal as much as 11-points from the Liberals. It's more than what we have observed in the past. And remember, I'm using a poll very favourable to the Green!

So back to my question: why running in a riding where the Gren party was low in 2008 and where the NDP is low as well? That doesn't make any sense. On the other hand, the current projections place the Green at 36% in Guelph and 28% in Bruce-Grey. In both case, if you add the May effect, you would get a win for her and her party (especially in Guelph). So why did she decide not to run in one of those ridings? I don't know. Let me know if you have a theory.

I'll modify the model to take into account of this May effect of course.