Survey researchers inevitably face the problem of item non-response; that is, some respondents provide valid answers to some questions, but provide invalid answers to others, such as “don’t know,” “no opinion,” or “hard to say.” However, including only those respondents who provide valid answers for each question may bias the estimates, because non-response does not occur randomly. This study applies a selection bias model to the problem of item non-response and tries to answer the following questions: in what situations might item non-response cause estimation bias, and in which ways might we correct for this bias?

By employing survey data collected by Taiwan’s Elections and Democratization Studies Project on the 2004 Presidential Election (TEDS 2004P), this research applies selection bias models to three topics of interest in the survey-vote choice, political efficacy, and position on the independence-unification issue. The research findings show that the vote choice model estimates may suffer from serious selection bias because non-respondents tended to be pan-blue voters and to vote for the pan-blue candidate. In the political efficacy model, non-respondents tended to be pan-green voters and also to have higher levels of political efficacy. Estimates for that model may therefore also suffer from selection bias. In the independence-unification issue model, by contrast, the factors affecting rates of item non-response were not systematically related to the respondents’ positions on the issue. Therefore, the model estimates do not suffer from selection bias. The research findings demonstrate that the seriousness of selection bias is not determined by the non-response rate per se, but rather by the degree to which response rates are systematically related to particular answers to a given survey question. The selection bias model can provide a satisfactory way to correct for estimation bias introduced by item non-response.

Transitional justice pertains to the challenge of reckoning with legacies of widespread or systematic abuses of human rights committed by agents of predecessor regimes. It has become a troubling political issue after a spectacular series of regime transitions in the late twentieth century, and the phrase ‘transitional justice’ today generally refers to a range of measures that new democracies implement to address the issue. There is a vast literature on the subject of transitional justice. However, the majority of research adopts the empirical approach and deliberately eschews the normative issues, and therefore questions concerning the nature of the wrongs that measures of transitional justice are meant to rectify as well as which measures we should adopt in order to adequately address this issue are not answered satisfactorily. In response to this absence of a coherent theory that can address both the past injustice and today’s needs to justify the pursuit of transitional justice, this article attempts to outline a normative theory of this kind by way of an interpretation of Isaiah Berlin’s value pluralism at the core of which is a tragic vision of politics. This theory understands the historical wrongs as a case of tragic value conflict and argues that if the same mistakes were to be avoided in today’s pursuit of transitional justice, we should take seriously the tragic experiences of both the alleged perpetrators and the victims. This value pluralistic theory of transitional justice is of significance to issues like civic education, the implementation of the rule of law and the re-writing of history in the newly-democratized societies. Furthermore, through this attempt this article also hopes to demonstrate that political philosophy is of valuable use to public affairs.