Invalid Ballots and Electoral Competition

We study how the closeness of electoral race affect the number of invalid ballots under the traditional paper-ballot voting technology. Using a large dataset from the Italian parliamentary elections in 1994-2001, we find a strong positive correlation between the closeness of electoral race and the fraction of invalid ballots. This correlation is not driven by voters' behavior, the biased actions of election officers, or the strategic pressure by parties. The theory that garners most support is that of unbiased election officers that increase their effort in response to higher (expected) closeness of electoral race, so as to reduce the likelihood of incorrectly adjudicating the victory. We also find large North-South differences in the patterns of invalid ballots: (i) electoral districts and municipalities in Southern Italian regions have a substantially higher level of invalid ballots, and (ii) the correlation between the closeness of electoral race and the fraction of invalid ballots is absent in the South. Social capital and organized crime explain these differences: once these two features are accounted for, the districts and municipalities in the South behave similarly to those in the North.invalid ballots; electoral competition; social capital; voting technology; Italian parliamentary election