Party-switching Between Elections is Influenced by Polarization, not the Number of Parties

Party-switching Between Elections is Influenced by Polarization,           not the Number of Parties
Yves Dejaeghere and Ruth Dassonneville

In 1979 Mogens Pedersen published a seminal paper in which he analyzed the impact of party-system variables on inter-electoral volatility. By means of an analysis of aggregate data from over 100 elections, he concluded that the number of parties increases volatility. Although Pedersen tested his hypothesis with the best data available at the time, they were actually not ideal to do so, as he indicated himself that his hypotheses implied ‘a test on the basis of individual level data’ (Pedersen, 1979: 16).

Switching parties between two elections is clearly something that needs to be investigated at the individual level. Using raw election results does not allow the researcher to know how many people actually switched from one party to another or from abstention to voting. As a result, the ideal data to investigate what party-system variables drive party-switching (and not turnout or the vote choice of new voters) are comparative individual-level survey data.

Only recently, such data have become available, as a recall question asking the respondents their previous electoral choice was added to the Comparative Study of Electoral Systems (CSES) questionnaire as of the second wave. Even though we have to take into account the limitations of recall data, they allow operationalizing vote switching at an individual level. Making use of such an operationalization, we can investigate what elements of the party-system influence the probability that individual voters switch parties between elections? We investigate this by means of an analysis of almost 30,000 voters in 33 elections. Continue reading “Party-switching Between Elections is Influenced by Polarization, not the Number of Parties”