Extracting Ideal Point Estimates from Actors’ Preferences in the EU Constitutional Negotiations

This article uses the Domestic Structures and European Integration (DOSEI) data set of actors’ preferences on 65 issues in the 2003-4 Intergovernmental Conference to extract the underlying preferences of the governments, the Commission and the European Parliament on the main dimensions of conflict in the European Union’s constitutional negotiations. The analysis starts by comparing the ideal point estimates produced by three ‘inductive’ techniques: exploratory factor analysis, NOMINATE and Optimal Classification. The results are a series of ideal point estimates that do not correlate well with some simple a priori assumptions about key actors’ positions on the reform of the EU. The analysis then proceeds with a ‘mixed’ deductive/inductive method, in which responses to the survey questions relating to the two exogenous dimensions of constitutional design in a multi-level polity (the ‘vertical’ and ‘horizontal’ allocation of power) are used to generate ideal point estimates on these two dimensions. The result is a more intuitive set of ideal point estimates for the 28 main actors in the negotiations.