我國立委選制改為單一選區兩票制的混合選制,是否發揮選制改革者的預期制度效應?這是本文所要探討的主要問題。研究發現立委選舉在2008年採行新選制後,有效政黨數立刻從2004年的3.28降為1.60;政黨的得票率與席次率之間的比例性,則從2004年的0.922降為0.776。選舉結果顯示FPTP制縮減政黨數目的機械性效應強大,國民黨以55.8%的得票換得77.2%的席次,在席次上增加了21.5%的紅利;相對地,民進黨以39.8%的得票率,只換得16.5%的席次,而浪費了23.3%的選票,其他小黨如親民黨、台聯及新黨在新選制下幾乎沒有生存空間。在此同時,新選制不僅明顯壓抑小黨的生存空間,同時也壓縮獨立人士的參選空間,參選率從最高的35.7%降至14.1%。至於新選制能否降低賄選情形及提高立法委員素質,選民的評價相當分歧,且評價結果深受選民政黨認同與選舉結果的影響。
The electoral system is the most fundamental mechanism for a democracy. It affects the development of party systems and even the operation of democratic politics in a given society. This paper concern about reform of the electoral system in the Legislative Yuan is whether this would reduce the negative influences of SNTV System on political system. This study analyzes the impact of electoral system on party representation, confirming that FTPT System would scale effective number of parties down in the congress, and cut the number of independent candidates to participate in the election. However, there were not evidences to support that Parallel Mixed-Member Electoral System would mitigate election bribery, and improve quality of Legislators.