Vancouverites like me will elect their new mayor next Saturday (although advance voting is open from the 10th until the 17th). After 3 terms, Gregor Robertson (Vision Vancouver) decided not to run again (his party is not even running anyone for that matter!), which led to a fairly open race this year.
I haven't made projections for municipal elections in the past, except for one article last year for the Montreal race. It's quite different from regular projections since I don't need to project seats or anything. While it might seem easier (it technically is), there are a number of other differences making mayoral projections more tricky. I get back to them below.
But first, for those of you who don't have the time to read a long text, here are the current projections for the mayoral election of Vancouver. The vote range is the 95% confidence interval.
So, how did I come up with these numbers? I mostly used the few polls we got.
We got only two firms polling this race, Research Co (formerly Insight West) and Mainstreet Research. Although the latter only polled once in early September (back when Vision Vancouver still had a candidate). I asked on Twitter and Mainstreet told me they weren't sure if they'd release another poll. Research Co. will, but they want to release as late as possible.
Not only have we had few polls, municipal polls aren't usually as accurate as provincial ones. That could partially be due to the fairly small sample sizes (around 400 for Research Co., 862 for the Mainstreet one). When I took a look last year at previous elections in Montreal and Calgary, I found that the corresponding effective (i.e: empirical) margins of error were close to 10%! This is much worse accuracy than other Canadian polls. Polls did better for the previous Toronto mayoral election and they were not too bad last year in Montreal. Still, there is no question that I need to include more uncertainty into my simulations.
There is also a very large number of undecided. Provincial or federal elections usually only have around 10% of undecided by the end of the campaign. The Mainstreet poll had over 40% of voters still not sure while the most recent Research Co. has them at 35% (and 3% that wouldn't vote). This alone should convince you of the level of uncertainty that exists. Polls usually allocate these undecided proportionally (which is equivalent to either assuming the undecided will vote as the decided voters or that they won't vote at all; both assumptions being quite unrealistic but that's the typical method used by Canadian pollsters for any election).
So, how will these undecided ultimately vote? Your guess is as good as mine! But there are enough of them to allow Ken Sim to finish ahead of Kennedy Stewart despite being about 10 points behind originally. We could also imagine that Sim, being the official NPA candidate (the main party in Vancouver and favorite according to the Mainstreet poll), could benefit from a bigger "get out the vote" campaign and machine than Stewart who is running as an independent (he's a former NDP MP from Burnaby). Or Shauna Sylvester will benefit from polling better among the 55+ who are more likely to vote.
My job here isn't really to guess which scenario will happen but instead to model this uncertainty. While I hate when people say "don't trust the polls, anything can happen", I have to admit they aren't completely wrong (the most Quebec election, earlier this month, was a good example of how wrong polls can be). So I went with a mix of the polls and various allocations of the undecided, along with the general uncertainty that comes from the fact that polls aren't perfect measures.
So I went with a poll average where half the undecided would break proportionally (in average; During my simulations I varied this ratio from 0 to 100%) and the other half would be uniformly distributed among the candidates. For the simulations, I also used margins of error of 10% to include enough uncertainty (just to put that in perspective, this means having a simulated sample size of around 100 people only!). Side note: the Mainstreet poll included the candidacy of Campbell for Vision Vancouver before he decided to withdraw. I thus adjusted this poll to reflect the fact he's not candidate anymore and his withdrawal is likely going to help Stewart and Sylvester more (If you compare the two Research Co. polls before and after Campbell withdrew, you'll observe these two candidates going up). Doing so made the Mainstreet numbers fairly close to the Research Co. ones, so it seems the two pollsters are agreeing this time and we won't have a repeat of the Calgary race (although they didn't fully agree on where Ken Sim or Hector Bremner were).
As you can see, despite a ton of uncertainty included in my model, Kennedy Stewart is clearly favourite. A 10 points lead isn't completely safe, especially with that many undecided, but it remains a lead that is hard to overcome. Stewart is ahead in every poll over the last two months.
A surprise is possible but this exercise should put things in perspective: it'd take a fairly massive polling failure for Ken Sim to finish ahead. Still, the polls used in these simulations aren't super recent (except for the latest Research Co. which was given a bigger weight), something to keep in mind. I'll update as soon as we get new numbers.
Remember as well that my model doesn't explicitly account for turnout. But the very large margins of error (plus the various allocations of the undecided) should at least give us the range of possible outcomes, if not the exact probabilities.
Google Trends
We can try to use other indicators of the state of the race. One is Google Trends. I have been using it for a few years now and while I do not think it can replace polls (not even close), it does usually provide some information (for instance during the recent Quebec election, it was clearly showing that Quebec Solidaire was popular).
If we look at the last 30 days, we get the following:
Kennedy Stewart is still ahead but it's much closer behind him. Please notice that I have used the "search term" method which is inferior to the topic search one. But the latter is impossible because most of the mayoral candidates aren't even known to Google (if you search for Justin Trudeau for instance, Google Trends will know it's the Prime Minister of Canada).
Is the race closer than what the polls are showing? Maybe. It might be more indicative of the search habits of younger voters however (which would explain why Hector Bremner is higher). Still, given the limited data we have, I found it interesting. At the very least, this gives us a confirmation that Kennedy Stewart is most likely ahead.
