Projecting backward - Macleans.ca

Projecting backward

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Alice Funke challenges the seat projection phenomenon.

The inherent bias in seat prediction methodologies to favour previous election results means they tend to overly favour parties set to lose seats, such as the Liberals and Bloc Québécois in the last election. They also tend to miss the likelihood of parties on the rise to gain seats, such as was the case with the Conservatives in the last election. Only the NDP, whose vote intention numbers showed little gain by the end of the 2008 campaign, saw seat count predictions on both sides of its eventual total.

Another problem for the seat projection methodologies is that they are backward-looking. They’re using days-old polling data at a time of incredible movement in the polls, and laying that on top of results from the last election when incumbency was a factor for some political parties’ votes that is no longer at play.