By-Election Barometer

By-elections are the only electoral tests that parties face between elections. But being hyper-local, they can be unpredictable. The By-Election Barometer serves as a measure of what might be expected in by-elections and of what actual polls are showing, in addition to providing a basis for comparing expectations to results.

A record of forecasts vs. results can be found below - the barometer has only made the wrong call six times in 54 federal and provincial by-elections since 2012, for an accuracy rating of 88.9%.


Three of the four errors have occurred in Newfoundland and Labrador, where the Liberals have gone from a tiny share of the vote in 2011 to big by-election victories. In one of the ridings, there was a swing of almost 90 points between the Tories and the Liberals.

In one of the other errors, the Progressive Conservatives won the Alberta riding of Calgary West by 2.8 points over Wildrose, who were favoured. In the model, Wildrose was given a 65% chance of winning, with the Tories at 35%.

In the other, the Liberals defeated the Coalition Avenir Québec in the riding of Chauveau. A popular former MNA, Gérard Deltell, had resigned, and the Liberals had a star candidate to go up against the star candidate that the CAQ found.

What the By-Election Barometer is

The By-Election Barometer tracks all scheduled and upcoming federal and provincial by-elections. The percentages shown in the charts represent margins, colour-coded according to the standards adopted by this site. The first set show the results of the last two elections.

The second set of margins are those that the projection model churns out when each regional/provincial poll is applied, using the same system as ThreeHundredEight's standard seat projection model. These are a way to demonstrate what might be expected in the riding, based on regional trends. The rolling 30-day average calculates an unweighted average of these projections with the last 30-days of regional polling.

The third set of margins, when available, represent the results of actual polls of the riding that have been released.

Finally, ThreeHundredEight's Forecast is calculated by taking the projected range of results from the average of the last 30 days of polling, including any polls done for the riding itself, and comparing how the ranges for each party overlap. The amount of overlap that potentially puts a party in a position to win is then tallied, the result being a percentage "chance" of that party winning the riding.

A Strong result means a 95% to 100% chance of winning, Likely is a 75% to 94% chance, Lean is a 60% to 74% chance, and Toss-Up means the chances of a party winning are 59% or less.

The Wildcard section describes any factor that could make the result unpredictable.

What it isn't

The By-Election Barometer is not a poll, the section titled "Margin after application of swing from regional polls" is not a list of riding polls, and the 30-day average is not a projection. By-Elections are notoriously hard to call, and the Barometer is not a tracking of actual voting intentions. The forecast is also not an opinion. As always, I am tied to what the numbers show.

Upcoming By-Elections

By-elections have been called in the provincial ridings of Calgary-Foothills in Alberta and Simcoe North in Ontario for September 3.

Garfield Dunlop resigned his seat of Simcoe North in order for the new PC leader Patrick Brown to have a seat in the Ontario legislature.

Leaders don't always get a free pass in Ontario, as John Tory discovered in his third attempt to enter the legislature after failing to secure a seat in the 2007 provincial election. But Brown is not much of a 'parachute candidate' in this riding, as he represented the adjacent federal riding of Barrie up to his leadership victory earlier this year.

On paper, this should be an easy riding for Brown to win. Dunlop represented it for 16 years, and his worst performance came in 2014 when he took 44% of the vote. His scores generally hovered between that 44% and 55%, with the Liberals usually taking between 31% and 39% (with the exception of 2011, when the Liberals tanked to 22%). The NDP has been good for 16% or 17% over the last two elections, and so shouldn't be much of a factor.

Considering that Brown is doing at least as well as Tim Hudak did in 2014 (and in most polls he is doing respectably better), and that the Liberals have dropped quite a bit in popular support, Simcoe North should be retained by the PCs without issue. There might be more of a race for second spot between the Liberals and the NDP.

It is hard to call this a Dunlop riding, despite his long history as its MPP. The federal Conservatives have done well in this riding over the last few elections as well. The wildcard is, instead, Patrick Brown. Will voters like having a (relatively) local boy and party leader as their MPP, or will they resent the switch? Since the by-election will be about Brown, will voters embrace him or reject him?

There is always the potential for a surprise when a by-election is centered around one issue or one individual. But all the fundamentals point to an easy victory for the PCs in Simcoe North.

Forecast history: Was STRONG PC from Dunlop's resignation.

Forecast percentages represent chance of winning
Residents of Calgary-Foothills will be asked to vote for the third time in a year thanks to the resignation of former premier and PC leader Jim Prentice before the count was even over on election night.

That is perhaps the biggest wildcard in this by-election. If it was taking place in any other riding, and a little further out from the provincial election of May 5, the PCs would be favoured to hold on. But there was a lot of disgust with Prentice's resignation, and it can't but be a problem for whoever runs under the PC banner this time.

Because otherwise, this would be an easy riding for them. Like many ridings in Alberta prior to the May vote, it had been represented by a Tory since time immemorial. No other party has ever won the riding since it was created for the 1971 provincial election.

From 1993 to 2004, the PCs won Calgary-Foothills with a majority of the vote. Their advantage was reduced in 2008 as the Liberals made a run at it, but a 20-point margin was re-established in 2012. When Jim Prentice needed a seat, it was provided by Len Webber and Prentice won a by-election in October 2014 with 58% of the vote to 30% for the Wildrose candidate. The unsuspecting NDP candidate took just 4%.

But the 2015 election flipped everything on its head. Prentice won 40% of the vote, his party's lowest share in the riding since the 1980s. The NDP surged into second place with 32%, while Wildrose captured 18%.

There has been one poll out since the election in Alberta, and it shows the Tories down a little, the NDP down a bit more, and Wildrose up big. On paper, this would make the riding a toss-up between the PCs and Wildrose, with the NDP having a very outside chance of taking it.

But there are so many other factors at play here. How angry will voters be at Prentice, and will they take it out on the PC candidate? Will voters there want to get on board with the NDP government, or take this first opportunity to express displeasure at the result? And if Wildrose is now the party seen as the main alternative to the NDP, will they garner enough of the non-NDP vote to win? It is a toss-up in every sense of the word.

A riding poll by Mainstreet Research agrees. Conducted August 18 and surveying 543 voters, it put Prasad Panda of Wildrose at 29%, just ahead of the NDP's Bob Hawkesworth at 26%. The PCs were at 20%, the Liberals at 12%, and both the Greens and Alberta Party at 7% each. The margin of error for the sample of decided voters would be almost five points, technically putting all three leading parties in the running - which is also the current forecast.

Forecast history: Was TOSS-UP (PC/WR/NDP) from Prentice's resignation.