Abstract:Candidates listed first on the ballot paper regularly receive more votes than other candidates. Experimental studies from first-past-the-post systems show that this ballot position effect is causal, not just a result of parties affording top positions to popular candidates, and stems from the physical ordering of candidate names functioning as a cue to voters. Does this also hold for PR systems where voters may avoid the challenge of choosing a specific individual candidate and instead simply vote for a party? We identify a natural experiment in the Danish simultaneous local and regional elections -pure list PR systems -where the ballot design make the allocation of some top positions as-if random. Based on election results for more than 10,000 candidates, listed on 103 different ballot papers, we find that ballot position, indeed, also has a causal effect on election results in PR systems. Our findings indicate that the empirical domain of ballot position effects is much wider than suggested by previous research. ____________________ * The first draft of this paper was presented at NOPSA 2014 in Gothenburg, Sweden.. We very much appreciate the constructive comments by participants in the workshop on Causal Effects in Political Science. We also appreciate the very competent and helpful research assistance from Lea Lauridsen, Katrine Wied Thomsen, and Niels Bjørn Grund Petersen. 2The question of whether a top position on the ballot paper affords a candidate an advantage over his or her fellow candidates in an election has a long history, both in political science and in practical politics. At the beginning of the twentieth century, Woodrow Wilson made an observation that summed up speculations that were to last until the present days:I have seen a ballot of this kind which contained seven hundred names. It was bigger than the page of a newspaper and was printed in close columns as a newspaper would be. Of course no voter who is not a trained politician, who has not watched the whole process of nomination carefully, who does not know a great deal about the derivation and character and association of every nominee it contains, can vote a ticket like that with intelligence. In nine cases out of ten, as it has turned out, he will simply mark the first name under each office (Wilson 1912: 593).Since then, a considerable body of political science research has been devoted to identifying more exactly the effect of being listed first on the ballot. Many studies find positive effects but many studies also find, that the contingent effects suggested by Wilson -publicity, engagement, educated voters and many other factors -may modify or even nullify ballot position effects (e.g. Chen et al. However, identifying ballot position effects with some accuracy is challenging. The reason is that political parties and candidates are likely to anticipate them and act strategically to harvest them. If being listed first really brings electoral advantages, parties and candidates are likely to actively seek this position on th...