Taking Electoral Competition Where it Belongs: Comparing Individual-Level and Election-Level Measures of Political Competition

Volatility is a key feature of party systems. The net change of party strengths in two consecutive elections is usually assumed to display the dynamics of party competition. Therefore, volatility is often used as a measure of the party system component of political competition. Some authors argue that the more the shares of parties change between two elections, the more competitive the system is. Others use volatility as a moderator for the vote or seat margin between two candidates or parties. However, using volatility has some flaws. Aggregate volatility – used as an indicator of electoral risk – underestimates in nearly every case the amount of individual voting shifts, which, in turn, builds only on a subset of the available electorate. Building on the conceptual literature on political competition more broadly, we argue that volatility is a poor measure of electoral competitiveness leading not only to unreliable but even to invalid measurements. Instead, we focus on the individual-level component of political competition by taking the multiplicity of individual party preferences of voters into account. We thus propose a new measure of electoral competitiveness that is based on propensities to vote (PTV) as an operationalization of Bartolini’s concept of availability. This approach is more suitable to grasp the underlying reasoning of scholars utilizing volatility: the willingness of the voters to switch parties instead of actual individual voting shifts or aggregate volatility. The paper proceeds in three steps. First, we clarify the conceptual differences between availability, voting shifts, and volatility. We conceive each of these entities as a necessary condition for the following one. However, neither is being available to multiple parties sufficient for switching party choices, nor does switching parties translate directly into electoral volatility. Second, using data from the European Election Study (EES), we compare the measures of availability, voting shifts, and volatility for European countries since the 1990s. Based on this, we investigate when and under which conditions the relationships between these three indicators are more or less pronounced. In a third step, we provide an empirical analysis of the causes of changing levels of voters’ availability, vote switching, and electoral volatility. Relying on a number of indicators relating to the electoral demand- and supply-side (such as partisan dealignment, political sophistication, changing policy preferences, economic performance, and party system characteristics), we provide a statistical test of the similarities and differences in the determinants of these three indicators. Finally, we will discuss when and how electoral availability translates into increased levels of vote switching and electoral volatility. Our results have important implications and provide future pathways for the study of political competition.