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 once in 34 federal and provincial by-elections since 2012, for an accuracy rating of 97.1%.


Note that the one error, in the Newfoundland and Labrador riding of Virginia Waters, was won by a handful of votes by the Liberals, who were given a 33% chance of taking the riding by the model. The PCs were awarded a 61% chance of winning, two points above the bar for being considered a 'Toss-Up'.

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 yet to be called in the federal riding of Whitby-Oshawa in Ontario and the provincial riding of St. George's-Stephenville East in Newfoundland and Labrador.


The untimely death of former finance minister Jim Flaherty has left the riding of Whitby-Oshawa vacant.

The riding has been a Flaherty riding for some time. Though he only first represented the riding after the 2006 election, when he won 44% of the vote in a relatively close contest with the Liberal incumbent, he represented the provincial riding of Whitby-Ajax for the Tories before that. When he made the jump to federal politics, his wife Christine Elliott filled in and has held the riding since.

Flaherty's margins of victory were much larger in 2008 (51% to 26% for the Liberal candidate) and 2011 (58% to 22% for the NDP candidate), so it seems unlikely that the riding is seriously at play. A good NDP or, in particular, Liberal candidate could make a run at the seat but the Conservatives remain the strong favourite to hold the riding.

Forecast history: Was a STRONG CONSERVATIVE at Flaherty's death.


The resignation of Newfoundland and Labrador cabinet minister Joan Shea means a by-election in the western Newfoundland riding of St. George's-Stephenville East will be held.

It is a riding that has gone back and forth between the Liberals and Progressive Conservatives in its history, though it has stuck with the PCs since 2003. It has generally gone with the prevailing mood of the province, which would seem to be a good omen for the Liberals. The party is leading in the polls by a wide margin.

As the Liberals did quite well in 2011 in an overall bad election, the model gives St. George's-Stephenville East to the party in a landslide. But the Liberals were boosted by the presence of party leader Kevin Aylward, which suggests that, while the riding does still seem a likely Liberal pick-up, the margin may well be much closer. That the race will come in the midst of the PC leadership race gives the Tories a bit of a chance. If, in their second go at it, they can get some decent candidates it may boost PC fortunes. But the Liberals are riding high and should be favoured.

Forecast history: Was a STRONG LIBERAL at Shea's resignation.