Knowledge of the Electoral System and Voter Turnout

立法院在2008年第七屆立法委員選舉中，首次採用了單一選區兩票制（Mixed-Member Majoritarian Electoral System, MMM），其結合了單一選區多數決與政黨名單比例代表制兩種席次分配方式，與過去採用的「複數選區單記非讓渡投票制」（Single Non-Transferable Vote with Multi-Member-District system, SNTV-MMD）在制度特性上截然不同。本文主要目的是檢視選民對於新選制的瞭解，亦即選制知識的高低，是否將對選民之投票參與產生影響。從既有的文獻中發現，傳統研究或者假定選民對選制有充分的理解而無須納入分析，或者即便探討選制知識高低對投票行為之影響，往往將選民的選制知識本身視為外因變數（exogenous variable）。本文與過去既有之研究有三點主要的差異。首先，本文並不貿然假定選民對於兩票制的新選舉制度擁有充分的資訊與瞭解，而是以四個問卷題目來測量選民對新選舉制度的瞭解程度。第二，在選制知識的測量方法上，既有研究常直接加總選民答對題目的數目，作為選制知識高低的變數，本文則進一步運用項目反應理論（item response theory），建構一個「二參數項目反應模型」（two-parameter item response model）來估計各個測量項目對選制知識的區辨能力，進而建立一個屬於連續變數的選制知識測量。第三，本文認為選制知識在對投票行為的影響上，應是一個內因變數（endogenous variable），基於此一理論設定，本文結合兩個方程式同時估計選制知識高低的成因及其對選民投票的影響。分析結果顯示，選民的選制知識的確屬於內因變數，而在充分考量此一內因性後，證實選制知識對投票參有顯著的正效應：選民對新MMM選制越瞭解，參與投票的機率也越高；反之，對新選制越不瞭解，參與投票的機率也越低。

關鍵字

選制知識；投票；項目反應理論；內因解釋變數

並列摘要

Taiwan's new MMM legislative electoral system first implemented in 2008 was a sharp departure from the half-century long SNTV system. This paper examines effects of knowledge of the new electoral system on citizens' decisions to vote or not to vote.Existing literature on voting either assumes that voters are fully aware of the electoral system and thus ignores the effect of knowledge or at best assumes it is an exogenous factor. This study distinguishes itself from other related works in three respects. First, we do not assume that voters are fully aware of the new two-ballot electoral system and make their voting choices accordingly. Instead, we design a set of four survey questions to measure the degree to which citizens understand the new electoral rule. Secondly, instead of summing up the number of correct answers to these survey questions (i.e. the traditional ”raw score” approach) , we use a two-parameter item response model to estimate item loadings and then construct a continuous measure of latent knowledge. Thirdly, instead of assuming knowledge is exogenous, we build a two-equation simultaneous probit model to account for the effect of electoral system knowledge on voter turnout. This model is meticulously specified so that it allows for knowledge to be endogenous. We find that knowledge of electoral system is indeed endogenous and, in both SMD and PR ballot voting, higher knowledge of the new MMM system stimulates higher probability of voting after taking into account the endogeneity of knowledge.

並列關鍵字

political knowledge ； electoral system ； voting behavior ； item response theory ； endogenous explanatory variable

參考文獻

Hsiao, Yi-Ching、Huang, Chi(2010)。Straight- and Split-Ticket Voting under the Mixed-Member Majoritarian System in Taiwan: An Analysis of the 2008 Legislative Election。Taiwan Democracy Quarterly。7(3)，1-43。

Fu, Hung-der(2005)。Political Knowledge, Political Evaluation, and Voting Choice: A Study of Legislative Election of 2001。Journal of Electoral Studies。12(1)，39-68。

Lin, Chiung-chu(2005)。Political Knowledge among the Electorate in Taiwan。Journal of Electoral Studies。12(1)，147-71。

Shiao, Yi-ching(2009)。Perception of Electoral Rules and Voting participation: A Multilevel Analysis in 2008 Legislative Yuan Election。Chinese Political Science Review。47，29-58。

Lin, Tsong-yji、Wang, Shu-hua(2007)。Changes and Sources of Political Knowledge in Taiwan。The Soochow Journal of Political Science。25(3)，93-129。

國際替代計量

Knowledge of the Electoral System and Voter Turnout

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