Predicting the 2015 Canadian election

The Canadian general election will be held on 19 October. The most basic prediction method uses the full district (“riding”) vote information from the last election (in 2011), the current poll estimate for national level support for each party, and a model of changes in district votes. There are two main models used in predicting elections under First Past the Post (single-winner plurality in districts), namely Uniform (additive) Swing and Proportional (multiplicative) Swing.

Based on the aggregate poll at signal.thestar.com, these two models predict the following point estimates for the seat distributions (after scaling up to account for the increase in parliament size since 2011):

Multiplicative: CON 133 NDP 71 LIB 125 BQ 7 GRE 1
Additive: CON 145 NDP 85 LIB 101 BQ 6 GRE 1

NDP have lost a lot of support in recent weeks, but it still looks as though no party will have an absolute majority and CON will be the largest party.

UPDATE 19 October (NZ time): using the latest poll estimate the models now give:

Multiplicative: CON 131 NDP 72 LIB 128 BQ 3 GRE 1
Additive: CON 137 NDP 86 LIB 109 BQ 5 GRE 1

ThreeHundredEight.com predict: CON 120, NDP 71, LIB 141, BQ 5, GRE 1
Toronto Star predict: CONS 124, NDP 71, LIB 140, BQ 2, GRE 1

Let’s see the results tomorrow.

Leave a Reply

Your email address will not be published. Required fields are marked *