How far are we from a competitive election in BC?

The BC election is underway, although I wouldn't blame you for not knowing. I'm pretty sure you heard more about the new Supreme Court nominee in the US than the various promises from Horgan, Wilkinson or Fursteneau.

We only had two polls so far and while they showed the BC Liberals more competitive than we might have thought (given pre-election polls this summer), it remains that the BC NDP is clearly ahead and significantly favourite to win. I currently have the NDP with a 89% chance of winning a majority and another 4% chance of winning a plurality. The Liberals only have a 5% chance of winning more seats than the NDP (and 1% of a tie). For the Liberals to win the most seats, it would require a fairly large polling error. Still, BC has had a history of polling failures (2013, 2018). Make no mistake here, I'm not saying the Liberals have a 5% chances of winning even if they really only get 35% of the vote while the NDP is at 43.5%. No, what those probabilities are showing is that if the BC Liberals are polling 8 points behind, given the traditional polling accuracy, they have a small chance if the polls are underestimating them and their vote is efficient.

So, how far are we from a 50-50 race? One that would be... too close to call?

I ran my usual simulations (you can too by the way now that I put my code on GitHub) and, using the results, I then estimated a logit regression showing the chances for the BC Liberals to win the most seats as a function of their lead in the popular vote (negative numbers mean the Liberals are behind obviously). Here's the results:

BC doesn't have much of a difference between the popular vote and the seats. At least not given the distribution of the votes in 2017. Essentially, it's a 50-50 race if the Liberals are tied with the NDP in the popular vote (the 0 on the x-axis). Wow, such great work Bryan, thank you! In all seriousness, this is relatively rare in Canadian politics. We usually see a difference between the two with one party being able to win with fewer votes (PQ in Quebec, LPC at the federal level). So it might seem like a whole lot of work for nothing -- it isn't!

The BC Liberals have their chances as long as they are within 1 or 2 points of the NDP. It'd naturally require better vote efficiency (in other words: having their votes in the right ridings) but it's far from impossible. In this scenario, it'd likely come down to fewer than 10 ridings (most of which in the Metro Vancouver area).

So, to answer the question of this post: I'd say that if polls start showing the BC Liberals within 5 points of the NDP, we will start seeing the projections with the Liberals with good chances. The historical polling accuracy in Canada, over the various provincial and federal elections of the last 10 years, is an empirical margin of error just shy of 5%. Therefore, if the Liberals are polling 5 points behind, the odds that the popular vote is a tie are becoming quite good. Don't misinterpret what I'm saying. It won't be a 50-50 race if polls start showing the Liberals within 5 -- it simply won't be one where a Liberal victory would require a massive polling error.

In other words: we are a 3-points shift in the polls away from having what I'd consider a contested election. If polls continue to have the NDP 8+ points ahead, Horgan can sleep nicely knowing his bet likely paid off. Although a major polling error can't be excluded given the possible low turnout of an election held during a pandemic (and, as opposed to NB, during a phase where cases are increasing). That's a topic for another day though.