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Evaluating the Election Projections

With the votes mostly counted and almost all seats decided, it is now possible to evaluate the election projections and predictions. For this analysis, I have used data from the CBC Canada Votes at 11:00 am on October 22, 2019.

This analysis will examine eleven poll aggregators, Four analysis-based projections, and three polling firm models. 338 CanadaCalculated PoliticsCanadian Election WatchCBC Poll Tracker, Lean Toss UpLISPOP, Too Close to all, Visualized Politics@EarlWashburn@repdonsman456, and @politikstcan each aggregate multiple polls from different polling firms to predict the election. Election Prediction Project and Teddy on Politics makes predictions using an analysis process, which examines data from the public alongside general trends. Teddy on Politics and @kylejhutton made similar ‘gut-based projections’ of the election. EkosForum, and Mainstreet are polling firms who use their data to model the election results.

Liberals won 157 seats. Overall, we can see that all the poll aggregators except for Lean Toss Up underestimated support for the Liberals. All the analysis-based projections also underestimated the Liberal support. However, two of three polling firms Ekos and Mainstreet overestimated support for the Liberals. Ekos was the closest to the Liberal projections missing by one seat at 158.

The Conservatives won 121 seats. Every poll aggregator projection, except for Lean Toss Up and @politicstacan, overestimated support for the Conservatives. All three polling firms underestimated Conservative support. Calculated Politics was the closest Conservative projection missing by one seat at 122.

The NDP won 24 seats. Every projection overestimated NDP support. Lean Toss Up and Mainstreet were the closest to the NDP at 25. The Bloc won 32 seats and every projection except for Ekos and Mainstreet estimated Bloc support. Calculated politics were closest to the Bloc at 34.

The Green party won three seats. Seven projections accurately projected this result. The People’s Party of Canada won zero seats. Seven projections accurately projected this result as well. One independent won, fifteen projections predicted this result.

To evaluate the overall accuracy of the different projections two methods are being used. First, the projection for each party is subtracted from the actual seats won. The absolute value is then taken (i.e. if it is negative it is turned positive) and these values are added together. The second method involves taking the Sum of Squares difference. This is done by subtracting the difference between projection and result and squaring this value then adding these together. This value is then divided by 7 (for the 7 projections) and then the square root is taken to show the average difference between each individual projection. The results of the two approaches are relatively similar.

Mainstreet was the most accurate projection by polling firm with Ekos close behind. Lean Toss Up was the most accurate poll aggregator, and third most accurate. The Elections Prediction Project was the most accurate analysis-based projection and fourth overall.

Part of the accuracy is determined as a result of the models the polling firms and aggregators use to project the election. Some of the differences in accuracy can also be attributed to how the polling aggregators model the polls of the election.

When comparing how the poll aggregators did at projecting the election Lean Toss Up once again was the most accurate only missing the actual results by an average of one percentage point. It should be noted that some of the poll aggregators did not share the projections for the PPC of Independents.

While individual models varied slightly in their performance. Overall, the aggregators, analysis-based projections, and polling firms should be satisfied with how they performed at projecting this election. All models predicted a minority government and most projected the Liberals would win the most seats.

*Updated at 1:00 pm to include the final Mainstreet seat projections