Travail de recherche/Working paper
Résumé : In close elections, a sufficiently high share of invalid ballots - if driven by votermistakes or electoral fraud - can jeopardize the electoral outcome. We study how thecloseness of electoral race relates to the share of invalid ballots, under the traditionalpaper-ballot hand-counted voting technology. Using a large dataset from the Italianparliamentary elections in 1994-2001, we find a strong robust negative relationshipbetween the margin of victory of the leading candidate over the nearest rival andthe share of invalid ballots. We argue that this relationship is not driven by votermistakes, protest, or electoral fraud. The explanation that garners most supportis that of rational allocation of effort by election officers and party representatives,with higher rates of detection of invalid ballots in close elections.