意識形態、精英極化與選民投票抉擇：以Copula函數分析

本文以2004年至2020年間五次台灣選舉作為研究對象，通過測量意識形態在選民投票行為中的的重要性，探討了兩個研究問題：一、台灣選民是否逐漸出現了意識形態極化的現象？二、當選民感受到國民黨和民進黨之間存在顯著的立場差異時，是否影響了選民投票時對於意識形態因素的考量？考虑到意識形態和投票行為是一種非線性的關係，本文選擇了目前在政治學界被較少使用的Copula函數作為研究方法，用以測量相關性及尾部依賴情況。再通過Probit模型和经过調整後適用於二元類別變數的條件Copula模型，查看精英極化是否對選民極化產生了作用。研究結果發現，雖然2012年後出現了緩慢的上升趨勢，但整體上意識形態因素的重要性呈現出了「波動性」的變化。其次，選民對於精英極化的感知確實影響了選民的投票決策，認為兩黨之間意識形態立場差距較大的選民更看重意識形態因素，但是其影響程度在不同選舉、不同程度的「精英極化感知」中差別較大。綜合來看，目前沒有充分證據顯示台灣選民出現了意識形態極化的趨勢。

關鍵字

政治極化；意識形態；台灣選舉；尾部依賴； Copula函數

並列摘要

The research objects set up in this article are five Taiwan elections from 2004 to 2020. By evaluating the importance of ideology in voters’ voting behavior, two research questions are explored: 1. Have Taiwanese voters gradually become ideologically polarized? 2. When voters perceive a significant difference in the political stances between the KMT and the DPP, does this perception affect their consideration of ideological factors when voting? Considering that ideology and voting behavior are a non-linear relationship, this paper selects the Copula function, which is currently used less frequently in political science, as a research method to measure correlation and tail dependence. Then use the Probit model and the adjusted conditional Copula model for binary category variables to see if elite polarization has an effect on voter polarization. The findings suggest that while there has been a slow upward trend since 2012, the overall importance of ideological factors has shown a "volatility" change. Second, voters' perception of elite polarization does influence voters' voting decisions, and voters with large ideological gaps between the two parties value ideological factors more, but their degree of influence varies greatly in different elections and degrees of "elite polarization perception". Taken together, there is currently no sufficient evidence to show that Taiwanese voters are experiencing ideological polarization.