Replication Data for: Does the Early Bird always Get the Worm? First Round Advantages and Second Round Victories in Latin America

Runoff systems allow for a reversion of the first-round result: the most voted candidate in the first round may end up losing the election in the second. But do voters take advantage of this opportunity? Or does winning the first round increase the probability of winning the second? We investigate this question with data from presidential elections since 1945, as well as subnational elections in Latin America. Using a regression discontinuity design, we find that being the most voted candidate in the first round has a substantial positive effect on the probability of winning the second round in mayoral races – especially in Brazil –, but in presidential and gubernatorial elections the effect is negative, though not statistically significant at conventional levels. The positive effect in municipal races is much stronger when the top-two placed candidates are ideologically close – and thus harder to distinguish for voters – but weakens considerably and becomes insignificant when the election is polarized. We attribute these differences to the disparate informational environment prevailing in local vs. higher-level races.

决选制度允许首轮选举结果出现反转：首轮得票最高的候选人，完全可能在第二轮选举中最终落败。但选民是否会善用这一规则空间？抑或是首轮胜出能够提升第二轮胜选的概率？本研究依托1945年以来的总统选举数据，以及拉丁美洲的次国家级选举数据，对这一问题展开实证分析。我们采用回归断点设计（Regression Discontinuity Design）开展研究，结果显示：在市长选举中，首轮得票领先的候选人对第二轮胜选概率具有显著正向影响——这一效应在巴西尤为突出；但在总统选举与州长选举中，该影响为负向，不过在常规统计学显著性水平下并不具备统计学意义。当首轮前两名候选人意识形态趋同（进而令选民更难区分二者）时，市级选举中的正向效应会进一步增强；而当选举呈现极化态势时，该效应则会大幅削弱并失去统计学显著性。我们将上述差异归因于地方选举与更高层级选举普遍存在的截然不同的信息环境。