Do Polls InBuence the Vote?

PO L L S P ROV I D E I N F O R M AT I O N A B O U T how well the parties are doing in a campaign. That information may affect voters’ perceptions of the various parties’ chances of winning in a Arst past the post (FPP) system such as Canada or the chances of being part of a coalition government in a proportional representation (PR) system. By affecting voters’ expectations about the outcome of the election, polls may affect the vote. How and why could expectations affect voting choice? The literature suggests two key reasons: strategic voting and a contagion effect. A strategic (or sophisticated or tactical) vote is a vote cast for a party that is not the preferred one, motivated by the intention to affect the outcome of the election (Blais and Nadeau 1996; Cox 1997; Blais et al., 2001). Typically, a strategic vote in a FPP election takes the form of supporting a second choice party that is perceived to have better chances of winning than the most preferred one. It appears that around 5 percent of voters cast a strategic vote in such elections (see Alvarez and Nagler 2000; Blais et al., 2001). Polls may affect strategic considerations because the latter are based on expectations about the outcome of the election. Polls may lead people not to vote for a given party because that party is perceived to be unlikely to win. Note that under such a scenario polls inBuence perceptions of the race, not preferences or evaluations of the parties. A second possibility is that polls affect expectations about the outcome and that these expectations, in turn, affect preferences or evaluations. In this case, voters come to evaluate parties more positively if their chances of winning appear to be good and to evaluate parties more negatively if their chances seem to be slim. This is the classical contagion effect: voters rally to the parties that are doing well in the polls.1