退黨對村里長選舉的影響：政黨—選民連結的效應（2010-2018）

政黨對於候選人而言，扮演相當重要的角色，她不只使選民更容易認識候選人的立場，也能降低候選人的宣傳成本；然而，近年來「個人化政治」的風潮興起，就連我國基層的村里長選舉也出現了退黨的現象，本文好奇如此情況將會對選舉結果造成何種影響？不同政黨對於候選人的效果又有什麼差異？為理解政黨在地方政治與選舉中的重要性，本研究以Kitschelt and Wilkinson(2007)對政黨和選民間聯繫方式的區分，也就是「政黨—選民」連結（party-voter linkage）視角出發，建構理論並進一步解釋「侍從式」(Clientelism)與「綱領式」(Programmatic)兩種「政黨—選民」連結類型，將會透過何種機制影響競選效果與選舉結果；藉由文獻梳理和資料檢證，我們初步發現民主進步黨和中國國民黨的確以不同的形式連結選民，而這也造成不同陣營的村里長候選人在退出政黨後有不同的選舉結果。本研究使用全國2010、2014、2018共三次村里長選舉結果作為實證資料，一方面確保研究對象間具有可比較的實驗與對照組，更容易形成穩健的因果推論(causal inference)，另一方面提供了全面性的經驗證據，更能帶來比較與對話的視角以理解我國地方政治的發展現況，特別是在普遍被認為和政黨關係不大的村里長選舉中，若能發現我國兩大政黨的根本差異，則更加凸顯「政黨—選民」的連結類型，對選舉的重要性確實不可忽略。實證策略部分，本文使用傾向分數配對(Propensity score matching, PSM)與三重差分法(Difference in difference in differences, DDD)以減緩內生性(endogeneity)。研究結果證實了本文研究假設：退出民進黨之村里長候選人，比起退出國民黨者，將減少9%~9.5%的得票率；這說明前次擁有民進黨籍者之候選人，因為其具有「綱領式連結」的特性，一旦退黨後將可能被其選民懲罰，相反地，透過「侍從式連結」的國民黨候選人若退出政黨，對於選民而言，並不影響地方服務與利益輸送的性質，得票率也不會因此降低。

關鍵字

政黨—選民連結；村里長選舉；因果推論；傾向分數配對；三重差分法

並列摘要

Party label is imperative to candidates as it allows voters to familiarize themselves with candidates at a lower cost. However, Personalized politics has been rising, and there has been a trend of candidates leaving their parties before elections in Taiwanese borough elections. This research seeks to examine the effect of leaving parties on the election outcomes and whether this effect is different from party to party. This research takes on the “Party-voter linkage” perspective established by Kitschelt and Wilkinson(2007), where the relationship between party and voters comes into either Clientelism or Programmatic. The thesis further constructs a theory to examine how different relationships influences the effectiveness of campaigns and voting outcome. Through literature review and data analysis, we found out the party-voter linkage was distinct between Kuomintang (KMT) and Democratic Progressive Party(DPP), and this difference decided the effect of party defection on election results. This article utilizes the Taiwanese 2010, 2014, and 2018 borough voting result data as the bases of analysis. The selected data includes a comparable experimental and controlled group, ensuring robust causal inference. Moreover, the borough election is nationwide, making the result of the analysis adequate as extensive empirical evidence. Furthermore, since borough election is generally considered less partisanship oriented, an outcome that shows a significant difference between KMT and DPP’s party-voter linkage can further highlight the importance of linkage types toward elections. In terms of empirical strategy, this research employs, Propensity score matching(PSM) and Difference in difference in differences(DDD) to tackle the endogeneity issues. The result verifies the hypothesis of this research: candidates who leave the DPP will have a 9% to 9.5% lower rate of votes than those who leave the KMT. In conclusion, the result shows Programmatic and Clientelism linkage has different effects on the election of the borough in Taiwan.