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The effective space of party competition

Dunleavy, Patrick and Diwakar, Rekha and Dunleavy, Christopher (2007) The effective space of party competition. PSPE working papers, 05-2007. Department of Government, London School of Economics and Political Science, London, UK.

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A conventional triangle display recommended by major authors has begun to be widely used for studying the patterning of party scores at constituency level across general elections. We show that it is systematically misleading in several ways and should not be further employed. To replace it we introduce the improved concept of ‘effective competition space’ (ECS) defined as the space of all feasible combinations of party vote shares, given the ‘number of observable parties’ (Nop) (defined as those with 1 per cent support or more). We employ a two-dimensional operationalization of the ECS concept to analyse changes across four Indian general elections, demonstrating that the space defined by the median constituency Nop captures well the variation of results. We also show that the effective competition space can be segmented in ways that respond to the context of each election but also facilitate meaningful comparison across them. We briefly show also how multi-dimensional versions of ECS operate. We conclude that greater attention should be paid to the factors driving changes in the number of observable parties, the key variable determining the size and patterning of effective competition space. More generally, we demonstrate the value of a relativized approach to measuring and comparing patterns across elections. Whenever an index score changes from one election to another, the frame within which the index scores are determined also often changes.

Item Type: Monograph (Working Paper)
Official URL:
Additional Information: © 2007 The Authors
Subjects: J Political Science > JC Political theory
Sets: Departments > Government
Research centres and groups > LSE Public Policy Group
Research centres and groups > Political Science and Political Economy Group
Date Deposited: 11 Sep 2009 15:43
Last Modified: 01 Oct 2010 09:27

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