Candidate visibility, voter knowledge, and the incumbency advantage in preferential-list PR

Our knowledge about how voters decide which candidate(s) to vote for under preferential-list proportional representation (PLPR) systems remains limited. In particular, it is debated whether incumbent MPs enjoy an electoral advantage over outsiders also under PLPR. We argue that such an incumbency advantage critically depends on candidate visibility (in the media) and differs across voters with varying levels of political knowledge. Our empirical analysis combines candidate information with rich individual-level voting data collected via “mock ballots” in the 2014 Belgian PartiRep election study. We show that the vote premium linked to incumbency increases with increasing media visibility, and while high-visibility incumbents outperform incumbents among the entire electorate, low-visibility incumbents enjoy an advantage only among knowledgeable voters. The results contribute to a better understanding of candidate voting and the incumbency advantage in PLPR. They also have implications for campaign strategies and the regulation of media access.