2011 / September

參選人競選支出效果及其外部性：單記非讓渡投票制下之黨內競爭性分析
The Effect of Campaign Spending and Its Externality: An Analysis of Intraparty Competition in SNTV

研究論文 Research Article

王鼎銘
Ding-ming Wang

341-370

參選人競選開支除了會影響自己的得票率，同時會對對手產生負面外部效果，這在過去歐美學界已頗具研究成果。本文擴充競選支出的相關理論到台灣單記非讓渡投票制（SNTV）的國會選舉，檢視學理上SNTV低當選門檻及同黨相爭的特性下，同選區同黨對手競選支出的負面效果，是否確實比他黨競爭者的影響來得大。2004年立法委員選舉是台灣唯一一次受「政治獻金法」規範下，採SNTV選制的國會選舉，本文利用從監察院及中選會蒐集的相關資料，以兩階段最小平方法（2SLS）分析參選人競選支出對得票率的影響。主要結論可歸納以下幾點：一、非現任的挑戰者競選支出會對選票增長產生正面幫助，而現任者支出對選票影響的邊際效果不僅遠低於挑戰者，反而對本身選票有負面的影響，此一發現吻合Jacobson（1978）所代表的傳統競選支出理論。二、來自黨外競爭對手支出的負面作用並不顯著，僅對現任者的選票產生一些影響，對原本票源就不充足的挑戰者而言更毫無作用。三、同黨競爭對手的支出會對同黨同志的選票產生顯著的負面影響，而且這種黨內互鬥的本質對擁有票源優勢現任者的直接影響較大，若與黨外對手支出的作用相較，更可發現跨黨之間的票源競爭性確實較黨內競爭性來得低。四、當同黨參選人數越多，同黨對手支出影響挑戰者的負面力道又會越強，顯示在這種協調機制較困難的情況下，同黨相爭對挑戰者的影響越嚴重。

Previous studies have shown that campaign spending not only plays an important role of attracting votes for the candidates, but also imposes a negative externality to their competitors. This paper expands the traditional campaign spending theory to Taiwan Legislative elections where the Single Nontransferable Vote (SNTV) is employed. Since SNTV endorses the characteristics of low electoral threshold and intraparty competition, we distinguish two kinds of opponents’ spending, spending of the same party and other parties, to capture their different influences. The data was collected from the Control Yuan for the 2004 Taiwan Legislative election, which is the only case with SNTV where the political contribution and campaign expenditures data are available. A two-stage least squares (2SLS) model is used to analyze the relationship between candidates’s spending and vote ratio. The findings can be summarized as follows. First, challenger’s spending has a positive effect on their electoral outcome, while the incumbents doesn’t. Second, the interparty competition is not severe, due to the insignificant influence of opponent’s spending from other parties. Third, the spending of same-party competitors has a significant negative externality on the electoral result, especially for the incumbent’s votes. Forth, the negative externality becomes more severe in the large districts. It indicates that the intraparty competition is more brutal when the coordination mechanism fails to function corresponding to larger district magnitude.

單記非讓渡投票制, 黨內競爭, 競選支出, 外部性, 負面競選
single nontransferable vote (SNTV), intraparty competition, campaign spending, externality, negative campaigning

政治學
Political Science

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