The predictive value of polls in a fragmented multi-party system: the Netherlands (1998–2021)
Abstract
Although vote intention polls are often used in the public debate as forecasts of future election outcomes, their predictive value has been subjected to scholarly inquiry. This research note contributes to the literature by assessing the predictive value of vote intention polls simultaneously at the macro-level (polls), meso-level (parties), and micro-level (voters). We analyse polls presented by the main polling agencies in the Netherlands (covering seven election cycles between 1998 and 2021), as well as micro-level panel data (covering 27,572 respondents and 46 polls between 2006 and 2010, and 35,574 respondents and 31 polls between 2010 and 2012). We reach three main conclusions. First, vote intention polls in the Netherlands generally do not provide more information than the previous election outcome, until the last few weeks of an election cycle. Second, the predictive accuracy of vote intention polls is lower for challenger parties than for non-challenger parties, particularly midway through the election cycle. Third, the predictive value for individual voters is generally very low, until the last few months before the election.
