A record of forecasts vs. results can be found below - the barometer has yet to make a wrong call in 23 federal and provincial by-elections.
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 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.
By-elections have been called for Dec. 9 in the Quebec ridings of Viau and Outremont. By-elections have yet to be called in the Manitoba ridings of Morris and Arthur-Virden, the Ontario riding of Niagara Falls, and the federal riding of Macleod in Alberta.
Weighted averages and support ranges
When available, polls for by-elections have been weighted using the same aggregation methodology employed elsewhere on the site. The methodology for the confidence intervals has been briefly explained here.
This Montreal riding is solidly and securely Liberal. Dubourg had won it three consecutive times (with the 2012 result of 47% being his worst) and prior to that William Cusano had held it since the 1980s. It has only elected a PQ MLA once, that being in 1976 when the PQ made its big breakthrough. Since then, the only time the Liberals have failed to take a majority of the vote was in the 2012 election.
Under new leader Philippe Couillard, the Liberals have experienced a boost in the polls and have especially made gains in Montreal. It makes Viau a riding that should easily remain in Liberals hands, the latest polls suggesting the Liberal candidate can win by a margin of about 30 points (only slightly less than Dubourg's last few performances). The Parti Québécois has traditionally been the runner-up party in this riding, but has rarely broke out of the 20% to 25% range (it took 24% in 2012). The CAQ is not a factor on the island of Montreal, but the performance of Québec Solidaire could be interesting. The party took 12% of the vote in Viau in 2012 and Gouin, the riding of party spokesperson Françoise David, is right next door.
Where the other parties end up in this by-election may be the only interesting thing to watch. The riding is a secure Liberal one, and Couillard's arrival only helps matters.
Forecast history: Was STRONG LIBERAL from Dubourg's resignation.
Outremont is a very safe riding for the Quebec Liberals - no other party has ever won it. Bachand won four consecutive elections, with the 2012 result of 42% being his worst (but he won the majority of the vote only once, in 2008). The PQ has only managed either 23% or 25% of the vote in the last three elections, while the CAQ finished fourth with 14% in 2012. Instead, it was Québec Solidaire that placed third in the last vote, with 18% support.
As Couillard will be running in this riding, both the PQ and CAQ have opted not to put a candidate up against him, more or less clearing the way.
Outremont should always be considered a safe riding for the Liberals, and with the party surging in the polls under Couillard there is virtually no chance of anyone else winning it. But the region has a history of going against conventional wisdom - it was the federal riding of Outremont (the territories are not completely contiguous) that elected Thomas Mulcair in 2007, against all initial expectations. A similar surprise by Québec Solidaire (who will not give Couillard a free pass) is unthinkable, but so was an NDP victory in Quebec once upon a time. It will be interesting to see if QS makes a serious run at the riding - and it would not be a bad idea, as it was their fifth best riding out of Quebec's 125 in the last election.
Nevertheless, Outremont is a very safe riding for the Liberals and should not go any other way.
Forecast history: Was STRONG LIBERAL from Bachand's resignation.
Morris has voted in a Progressive Conservative MLA for more than a generation, and Tallieu won the riding by a huge margin in 2011. Just with the riding's history, it would be considered a Tory lock.
That the PCs have improved their position in the polls over the last few months make the riding in even easier hold for the Progressive Conservatives. Barring some disaster, a PC MLA will represent the riding after the next vote. The more interesting may be for second between the NDP and Liberals.
Forecast history: Has been STRONG P.C. since Taillieu's resignation.
And it should be just as easy for the Progressive Conservatives to hold. The riding has been PC since the 1950s, and Maguire never won it be less than double-digits. In the last two provincial elections - in which the NDP formed the government - the margin was larger than 30 points.
With the Tories leading the NDP in the polls, it is virtually impossible that the PCs will not retain this riding with ease. It will be interesting to see how the provincial Liberals do, however. They have a new leader, and the party is polling relatively well outside of Winnipeg. Could they supplant the NDP for runner-up status?
Forecast history: Has been STRONG P.C. since Maguire's resignation.
Niagara Falls has been reliably Liberal since the party came to power in 2003, but that reliability is now in doubt. Craitor had won with comfortable margins in 2003 (nine points) and 2007 (16 points), but came to within a whisker of losing to George Lepp in 2011. He took 36% of the vote to Lepp's 35%, and the New Democrats were not far behind at 26%. For the Liberals, that was their worst result in Niagara Falls since 1995.
The riding has a checkerboard history, having been represented by the Liberals since 2003, by the PCs between 1995 and 2003, by the NDP between 1990 and 1995, and by either the Tories or the Liberals in alternating stints going back to the Second World War (and during part of the war, the CCF had the riding). Niagara Falls has been a bellwether riding since the 1980s, having been represented in government since the reign of David Peterson. Its history makes this a toss-up riding, and the current numbers also point to it being close.
The model gives the PCs the edge, with a 44% chance of winning to a 39% chance of winning for the NDP and 17% for the OLP.
With such a close race, it could be decided almost entirely by who the parties manage to recruit to represent them. The party that can attract the best candidate will almost certainly win. That may sound like an obvious statement, but we can all think of elections where the best candidate did not win, and was instead swamped by provincial or national trends. Niagara Falls could instead be a very personal contest.
Of course, the provincial government may not survive into March. And if it does, voters in Niagara Falls could be asked to go back to the polls again within a few months. But if the by-election in Niagara Falls is called soon, it should be a nail-biter.
Forecast history: Was TOSS-UP (OLP/PC/NDP) from Craitor's resignation. Became TOSS-UP (NDP/PC/OLP) on October 11. Became a LEAN NEW DEMOCRAT on November 8. Became TOSS-UP (PC/NDP/OLP) on November 29.
It is hard to find a safer riding for the Conservatives than Macleod. Menzies won it with 77% of the vote in both the 2008 and 2011 elections, after taking it with 75% in 2004 and 2006. Between the 1988 and 2000 elections, the combined tally of the Reform/Canadian Alliance and Progressive Conservatives in the riding ranged between 81% and 84%. The best the Liberals have done since then was just 16% in 1993, while the NDP has not done better than the 10% it took in 2011 over that time.
Macleod is as secure as it gets. The only battle in this riding will be for the Conservative nomination. Who places second may be an interesting footnote, but that is about it.
Forecast history: Has been, and will remain, STRONG CONSERVATIVE from Menzies' resignation.