Reverse Coattail vs Strategic Reversal: The Effect of District Legislators on Presidential Voting in Taiwan

This study investigates whether legislative incumbency in Taiwan’s mixed-member majoritarian system generates a reverse coattail effect in subsequent presidential elections. While prior work focuses on top-down dynamics, this study tests a bottom-up influence using a sharp regression discontinuity design (RDD) around close legislative races. To isolate local effects from national trends and strategic voter behavior, we subtract national party swings, using demeaned presidential vote change as the outcome. Descriptive patterns suggest strategic reversal: voters in incumbent-held districts often split tickets. However, RDD results show that incumbency increases presidential vote share, with effects conditional on context—most notably in open-seat races, southern districts, and Democratic Progressive Party (DPP) constituencies.