2014 年11 月29 日「九合一」選舉結果，國民黨遭受臺灣自有地 方選舉以來最嚴重的挫敗。在全部22 個地方首長中，從過去超過三分 之二的15 席，減少到不及三分之一的6 席。最令人矚目的是代表「在 野大聯盟」角逐臺北市長的柯文哲，打敗國民黨提名的連勝文，大贏連 勝文將近25 萬票，並中止了國民黨在臺北市長達16 年的執政地位，這 是前未有過的紀錄。選後國民黨的一份檢討報告指出，國民黨如此慘敗 的原因之一是「首都選戰影響外溢擴及其他縣市」。換言之，「柯文哲現 象」讓國民黨其他縣市選情連帶受到影響。
「柯文哲現象」是否真有如此外溢效應？本文以新竹市長選情為 例，透過一系列實證資料，運用「複層次結構非線性模型」結合個體與 總體資料分析，驗證「柯文哲現象」對民進黨新竹市長候選人林智堅的 外溢效果。研究結果顯示，在個體層次的變項上，新竹市選民對林智堅 的偏好、政黨取向及年齡，顯著地影響對林智堅的支持度。在總體層次 的變項上，柯文哲的支持度、媒體曝光度及電視新聞評論節目對柯文哲 的正面或負面批評，都顯著地影響新竹市選民對林智堅的支持度。研 究發現證實「柯文哲現象」的外溢效果，也就是所謂的「衣擺效應」 (coattail effects) 或「母雞帶小雞效應」存在。

In nation-wide local elections held on November 29, 2014, the Kuomintang (KMT) suffered its worst defeat in the post-war history of local elections in Taiwan. The party saw its control of the country’s 22 local executive posts dwindle from 15 to only 6. Most notable among the KMT’s setbacks was its mayoral election defeat in the Taipei City, which had been run by a KMT mayor for 16 years. Ko Wen-je, an independent who ran under the banner of a “grand opposition alliance,” defeated KMT candidate Sean Lien by nearly 250,000 votes. The KMT’s post-election review report pointed to spill-over effects from the Taipei election to other local contests as one of the reasons for its crushing defeat nation-wide.
Did the “Ko Wen-je phenomenon” truly produce such spill-over effects? This study looks at the Hsinchu City mayoral election, using various empirical data to assess potential spill-over effects from Ko’s Taipei candidacy to that of DPP Hsinchu City mayoral candidate Lin Chi-jian. Hierarachical non-linear modeling is applied to analyze a combination of individual-level and macro-level data. The data analysis shows that with respect to individual-level variables, voters’ preference for Lin Chi-jian, party-orientation, and age clearly influenced the level of support for Lin’s candidacy. At the macro-level, support for Lin was positively correlated with Ko Wen-je’s level of support and media exposure as well as positive commentary on Ko’s candidacy on television news programs. The results of the study confirm the existence of coattail effects of the Ko Wen-je phenomenon in Taiwan’s 2014 local elections.