Combining ideological and policy distances with valence for a model of party competition in Germany 2009
| Author | Anna-Sophie Kurella,Franz Urban Pappi |
| Published date | 01 January 2015 |
| Date | 01 January 2015 |
| DOI | http://doi.org/10.1177/0951629813515080 |
| Subject Matter | Articles |
Article
Combining ideological and
policy distances with valence
for a model of party
competition in Germany 2009
Journal of Theoretical Politics
2015, Vol. 27(1) 86–107
©The Author(s) 2014
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DOI:10.1177/0951629813515080
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Anna-Sophie Kurella and Franz Urban Pappi
University of Mannheim, Germany
Abstract
This paper addresses two problems: how can we identify a verisimilar policy space and how can
we detect Nash equilibria in this space for parties’ policy positions? We argue that the ideological
party positions that voters perceive are fixed during the time span of one electoral campaign
and that they constrain the policies parties offer the electorate in search of optimal vote shares.
We apply the valence model developed by Schofield to party competition during the German
federal election campaign 2009. First three issue scales are combined with a left–right scale to
form one homogeneous space in which equilibrium locations of parties are sought. The results
show that local Nash equilibria in this combined space depend heavily on the start values and
are implausible. Fixing the ideological dimension leads to a stable and meaningful equilibrium
configuration in which large parties move to more central positions and smaller parties move to
more peripheral positions in the policy space.
Keywords
Construction of policy spaces; issue voting; local Nash equilibrium; party competition; spatial
model
1. Introduction
Spatial models of party competition focus on strategies of parties for vote maximizing or
optimal policy attainment, whereas voting specialists explain the decisions of the general
electorate. These decisions are, to a large extent, standing decisions which parties cannot
influence in the short term. Combining ideological and policy distances with valence
constitutes an exercise in combining long- and short-term motives for the vote which
allows us to study constraints on party competition by the ideological reputations of
parties and by valence components. Ideological images of parties are fixed for longer
Corresponding author:
Anna-Sophie Kurella, Center for Doctoral Studies in Social and Behavioral Science, University of Mannheim
D7, 27, Mannheim 68159, Germany.
Email: anna.kurella@gess.uni-mannheim.de
Kurella and Pappi 87
time periods and important components of party valences, such as party competence,
are built on retrospective evaluations. Thus, the only factors of the original Michigan
model left for campaign strategies are issue positions. Here parties have some leeway
when planning an election campaign. In contrast to applications of spatial models which
rely exclusively on left–right positions, we analyze party competition assuming that the
space in which parties maneuver in order to reach their goals is made up of multiple issue
dimensions. When an ideological dimension such as left–right is added it will function
as a constraint on position taking, and not just like another dimension in an otherwise
homogeneous policy space. We will offer indirect evidence for this central hypothesis by
showing that plausible equilibrium positions in a combined ideological and policy space
cannot be identified.
The first task for a study of party competition is the selection of a model whose
assumptions are plausible for the party and electoral system of the chosen case and the
available data on the electorate. Thus, for Germany the model has to be suited to multi-
party systems under proportional representation and should be able to handle more than
one policy dimension. Judged from the consequences for possible equilibrium configura-
tions, an important question is what to assume concerning party motivations. Will parties
try to maximize vote shares or participation chances in the next coalition government
or are the strategies of parties better captured by imputing intrinsic policy motivation to
them? We will explain our choice in the following section.
Our second task is to clarify the type of policy space which we are ableto constr uct on
the basis of available data for the German federal election of 2009. In the literature on the
application of spatial models we find one-dimensional ideological spaces like left–right
or sets of issue preference questions in voting studies from which latent policy spaces are
derived by factor analysis etc. We will describe our data basis in Section 2 together with
a method for identifying verisimilar party positions as perceived by voters. Our aim is to
construct a policy space that combines concrete issues of the electoral campaign and the
ideological left–right scale, the idea being that parties are relatively free to choose issue
positions whereas they are constrained regarding their ideologicalimage in the electorate,
at least in the short run of an election campaign.
In Section 3 we will present our descriptive evidence for both issue and ideological
dimensions of the common policy/ideological space based on a pre-election survey of
the German electorate in 2009. We assume that a voter’s utility from a party is higher
the less distant the party position is from the voter’s issue preferences and ideological
self-placement. For each party we shall compare the distribution of their voter and sup-
porter ideal points on the ideological left–right scale and on issue scales for nuclear
energy, immigration and taxes versus social services. These three issues were debated
controversially during the election campaign 2009.
Section 4 is dedicated to equilibrium analyses. First we test whether the electoral
mean of the combined ideological and policy space fulfills the conditions of a Nash equi-
librium for the party strategies, when taking valence differences between the parties into
account. The result is ambivalent for the four-dimensional space. But holding the party
positions on the ideological space constant and searching iteratively for optimal issue
positions results in a configuration similar to the estimated issue positions but closer to
the electoral mean and gives realistic party vote shares. The fixed left–right scale impedes
full maneuverability of the parties, whereas otherwise implausible leap-frogging would
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