Challenges in Tracking Parties’ Positions in Multi-dimensional Policy Spaces by Manifesto Project data: A Dynamic Idealpoint Model and its Extensions. Martin El Zeppelin University, Friedrichshafen [email protected] Prepared for delivery at the Manifesto Project User Conference 4–5 June 2015 WZB Berlin Social Science Center e compilation of coded manifestos by the Manifesto Project is an invaluable resource for the reconstruction of parties political positions and their changes over time. Nevertheless, the extraction of political positions from these data is confronted by some considerable challenges. First, the relation between positions and counts or percentages – as present in these data – is essentially non-linear. Second, Manifesto data may reect both political positions and the salience of policy areas. ird, the policy space wherein parties take positions is not nec- essarily uni-dimensional. Fourth, positions taken by parties can be expected to be autocorrelated, since parties do not invent their positions in each election ex nihilo. Fih, it is unlikely that even the Manifesto data is free of measurement error and and that the policy topic categories used may vary in terms of their discriminatory power for policy positions. e paper points out how these prob- lems are addressed by recently developed models of the generating process of the Manifesto data. It further proposes some extensions to these models to address the remaining challenges. 1 1 Introduction Political positions of parties play a central role in many areas of research in comparative politics. In contemporary research on the formation and duration of coalition governments, political positions of potential coalition member parties play a vital role (e.g. Laver and Hunt 1992). Also, the full potential of spatial models of voting can be realized only if measures of candidates’ and parties’ political positions are used that are independent of the voters’ perceptions. Without such independent measures, spatial analyses of voting may fall victim to projection eects in voters’ assessment of the positions of candidates and parties (Brody and Page 1972; Wilson and Gronke 2000; Merrill et al. 2001). For the purpose of an independent reconstruction of parties’ political positions various methods have been discussed in recent years. e reconstruction of political positions from political texts usually starts with the identication of semantic or grammatical units, such as words (Laver and Garry 2000; Laver et al. 2003; Slapin and Proksch 2008), sentences or “quasi-sentences” (Budge et al. 1987, 2001a; Volkens et al. 2010), and proceeds with classifying these units into politically relevant categories and concludes with counting the occurrence of these political categories. Word count approaches have gained some popularity during the last couple of years, owing to the recent availability of easy-to-use soware for automatically generating such word counts. While some argue that word-count based reconstruction of political positions are at least competitive to sentence-classication based reconstructions (Laver and Garry 2000; Laver et al. 2003), the word-count approaches have not yet gained the same acceptance in the political science community as sentence-based approaches. One reason may be the wide availability of the data produced by the Manifesto Project, which are based on the categorization of quasi-sentences. e contribution of the Manifesto Project (Budge et al. 1987, 2001a; Volkens et al. 2010, 2013) to the reconstruction of political positions from political texts, in particular party manifestos – documents published by or on behalf of parties on occasion of elections – can hardly be overstated. ere is no source on Earth that rivals it in terms of temporal and geographical breadth when it comes to collecting, processing, and publishing such data. And a simple re- view of all the published literature that makes use of it may ll a whole volume. Nevertheless, the Manifesto Project data have not yet been brought to their full potential. ey are most widely used in the condensed form of the RiLe index, which summarises the many policy topics uncovered, recorded, and coded by the Manifesto Project and its precursors. is con- densation of the rich Manifesto Project data is motivated by the notion of an all-encompassing ideological le-right dimension, but there is more to nd in manifestos and more to nd in Manifesto Project data than that. Parties touch upon in their manifestos on a multitude of political topics that are relevant for a multitude of policy domains and it might well be that the positions parties take in their manifestos cannot be reduced to a single dimension, at least not without losing potentially valuable information. 2 e present paper discusses a recent aempt at bringing the data of the Manifesto Project to its full potential, the dynamic idealpoint model of manifestos (El 2013). e main pur- pose of this paper is to illustrate how this model can be used to reconstruct the positions of parties in specic policy domains, which may be multidimensional, how to describe the evo- lution of such positions, and how these positions can be used to distinguish party families. In addition, it indicates a couple of challenges that confront this dynamic idealpoint model and points to some ways to address these challenges in its further development. e paper is composed as follows: e next section sets out the basic ideas behind the development of the dynamic idealpoint model. It gives a theoretical justication for the use of manifestos as a base for the reconstruction of political position, resting on a notion of selective empha- sis, although this notion may be at odds with some of the original ideas that guided some of the principle investigators of the Manifesto Project. is section also discusses the funda- mental challenges in using the Manifesto Data, which have lead to the dynamic idealpoint model around which this paper is organised. e third section discusses some formal and technical aspects of the model. e fourth section illustrates the application of the dynamic idealpoint model to the reconstruction of parties position in two dierent policy domains, one unidimensional, the other two-dimensional, and to identifying the typical average positions of various party families. is section also discusses the use of such reconstructed political positions as independent variables in the analysis of paerns of voting behaviour. e h section discusses the challenges that confront the dynamic idealpoint model and possibilities of its further development. A sixth section discusses the problems that arise if the complexi- ties that the idealpoint model addresses are disregarded. As usual, the paper is concluded by a brief summary. 2 The Ideas Behind the Dynamic Idealpoint Model 2.1 Rhetoric, Position and Selective Emphasis When politicians make public speeches they usually claim what good, they have done for country and people or what good they plan to do, whether this means increasing prosperity, defending public security or upholding morality. Also, it has oen been claimed that many voters do not so much care about where parties or candidate stand on issues, but rather how parties or candidates have performed in oce. ese observations or assumptions have given rise to the concept of valence issues (Stokes 1963) and to the “valency and saliency” theory of party competition (Robertson 1976; Budge and Farlie 1983a). is theory also is said to have guided the coding of electoral platform by the Manifesto Research Group and the Comparative Manifestos Projects. e view that this theory purports has been aptly summarized by Ian Budge (in Budge et al. 2001b: 82): 1. Party strategists see electors as overwhelmingly favoring one course of action 3 on most issues. Hence all party programmes endorse the same position, with only minor exceptions. 2. Party strategists also think that electors see one party as more likely that the others to carry through the favored course of action. 3. Hence each party has a set of issues that ‘belong’ to it, in the sense that the centrality of these issues in an election will increase its vote. 4. A party therefore emphasizes its ‘own’ issues in its election programme, in an aempt to increase the salience of these for voters. It emphasizes ‘rival’ issues less or not at all. 5. Policy dierences between parties thus consist of contrasting emphases placed on dierent policy areas. is view also seems to have been corroborated by the fact that the electoral platforms coded by the Manifesto Research Group (MRG) and the Comparative Manifesto Project (CMP) mostly contain positive references to policy goals and hardly ever negetive references. Prima facie, assumptions such as these are necessary to justify the relatively low proportion of coding categories employed by the MRG/CMP that explicitly oppose a specic objective or state of aairs. Also, in Budge’s view the “valency and saliency theory” is well corroborated both by results of analyses of the manifesto data and by results of other scholars (Budge et al. 2001b: 82–83). However, some critical reections may lead to the conclusion that, on the one hand, these assumptions contradict rather than justify the use of MRG/CMP data to determine par- ties’ genuine political or ideological positions — quite in contrast to the common use of these data to assign le-right positions to political parties. On the other hand, these assumptions are neither completely plausible nor are they necessary to justify the use of