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.

决选制度可逆转首轮选举结果：首轮得票最多的候选人，最终可能在第二轮选举中落败。但选民是否会利用这一规则空间？首轮胜出是否会提升候选人赢得第二轮选举的概率？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，对这一问题展开探讨。本研究采用断点回归设计（Regression Discontinuity Design）展开分析，结果显示：在市长选举中，首轮得票领先的候选人对赢得第二轮选举的概率存在显著正向影响——尤以巴西为甚；但在总统选举与州长选举中，该影响为负向，不过在常规显著性水平下未达统计显著性。当首轮前两名候选人意识形态立场相近（即选民更难区分二者）时，市长选举中的正向影响会显著增强；而当选举呈现极化态势时，该正向影响会大幅减弱并失去统计显著性。本研究将上述差异归因于地方选举与更高层级选举所存在的截然不同的信息环境。