Abstract
Although comparative research has relied heavily on electoral volatility as a proxy for party system institutionalisation (PSI), this measure cannot account for the patterns of interparty interactions that are key to determine the degree of party system stability. I develop a new measure – the party bloc volatility (PBV) index – to account for consistency in the ideological positions and in the partisan composition of the government and opposition blocs. I demonstrate the limitations of the index of electoral volatility by analysing the case of Brazil. Although electoral volatility substantially decreased between 1994 and 2010, the patterns of interparty alliances became less and less predictable from 2002 onwards, as party fragmentation increased while interparty ideological differences decreased. In combination with a major economic and political crisis, these trends led to the discrediting of the established parties and thus favoured the rise of the extreme right in the 2018 elections.
Highlights
Resumo Embora o índice de volatilidade eleitoral tenha sido utilizado de forma massiva pelas pesquisas comparadas como uma proxy de institucionalização de sistemas partidários, essa medida não consegue dar conta dos padrões de interação interpartidária que são cruciais para determinar o grau de estabilidade do sistema
I propose a framework for analysing party system institutionalisation (PSI) and de-institutionalisation, which takes into account the dimension of stability, both in components of the system (Chiaramonte and Emanuele, 2017; Mainwaring and Zoco, 2007; Mainwaring et al, 2018) and in patterns of interparty interactions (Casal Bértoa and Enyedi, 2016; Mair, 1996, 2002)
I compare party bloc volatility (PBV) scores calculated for Brazil (1985–2018), Chile (1989–2014), and Bolivia (1982–2014) with other measures of party institutionalisation estimated for the same cases
Summary
Resumo Embora o índice de volatilidade eleitoral tenha sido utilizado de forma massiva pelas pesquisas comparadas como uma proxy de institucionalização de sistemas partidários, essa medida não consegue dar conta dos padrões de interação interpartidária que são cruciais para determinar o grau de estabilidade do sistema. I develop and test a new measure of PSI – the party bloc volatility (PBV) index – to account for consistency in patterns of government alternation and in the ideological positions of the governing alternatives.
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