出刊年月/Date of Publishing

2003.03

所屬卷期/Vol. & No.   第33卷第1期 Vol. 33, No. 1

類型/Type                 研究論文 Research Article

篇名/Title
Election Forecasting in the UK: The BBC’s Experience
英國選舉預測：英國國家廣播公司之經驗

作者/Author
柯萊．佩恩 Clive Payne

頁碼/Pagination
pp. 193-234

摘要
本文試圖評論過去30年來英國國家廣播公司對英國各類選舉預測所用之統計方法。這段期間英國曾使用下列三種選舉制度：第一，單一選區相對多數決制（用於國會大選、1999年之前之歐洲議會選舉，和年度地方政府選舉）。第二，全國性公民投票（用於加入歐洲共同體、威爾斯及蘇格蘭之權力下放複決案、成立大倫敦市議會之複決案，和愛爾蘭厄斯特協定）。第三，不同形式的單一選區制與比例代表制之混合選制（同於威爾斯、蘇格蘭，與倫敦市議會，及1999年後之歐洲議會選舉〔係區域名單比例代表制〕）。此外，筆者也分析下列三種選舉情境所用之預測方法。第一，早在選舉發生之前，運用民意調查資料系列及其他資訊所做之預測方法。第二，在投票口關閉後，運用投票口調查資料所做之預測方法。第三，在開票之夜，運用部分已開出的選票來預測最後選舉結果之方法。

本文描述英國特殊的選舉制度，導致其對選舉結果預測所用統計方法之選擇。並進一步與其他國家選舉預測相互比較。本文除了針對英國國家廣播公司在開票之夜所做的選舉預測的準確度做一評估外，更強調播報選舉預測時之媒體特質。

Abstract
The paper reviews the various statistical methods used by the BBC to forecast different types of election in the UK in the last thirty years. Elections in this period were of three main types:

• The Single-Member District Plurality system (West-minster Parliament, European Parliament until 1999, and annual elections for local government councils)

• National Referendums (Entry to the EEC, Welsh and Scottish devolution, London Assembly, Good Friday Agreement in Ulster)

• Variants of the Additional Member system used for the Welsh, Scottish and London assemblies post 1997, and the Regional List System used for the European Parliament in 1999 (PR regional list system)

The forecasting methods used in three different contexts are described:

• Predictions of the result before the election takes place using opinion-poll series and other data

• Predictions of the result as soon as the polling stations close using exit polls and other techniques

• Predictions of the final outcome on election night itself using the subset of actual results declared

The paper describes the special features of the UK electoral systems that determine the statistical methods used and includes comparisons with election forecasting in other countries. The BBC’s performance in election-night fore- casting over the period is assessed. Media aspects of the presentation of election forecasts are also highlighted.

關鍵字/Key Word
英國選舉、預測、民意調查
UK elections, forecasting, prediction, polls

DOI
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學門分類/Subject
政治學 Political Science