Locating Political Parties in Policy Space: A Reanalysis of Party Manifesto Data

Starting from a number of deficiencies in the Comparative Manifestos Project approach to studying left–right policy scales in election programs, an additive model based on the distinction between position and valence issues is proposed. This allows analysis of the policy space in established democracies under the assumption that left and right have different meanings from country to country and over time. The model is illustrated with regard to four Western European countries with different types of party system: Germany, Italy, Sweden and the United Kingdom. Empirical findings affirm that the procedures are workable and that the data generated are capable of yielding detailed information beyond that which previous approaches are able to deliver. In addition, preliminary tests on external validity produce reassuring results.