Neither the T Index nor the D<sub>2</sub> Score Measure “Two-Partyness”: A Comment on Gaines and Taagepera

Dunleavy, Patrick

doi:10.1080/17457289.2014.902841

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…These indicators are more sensitive to vote differences between the largest-and the second-largest party than the effective number of parties. For instance, a distribution of 67%-16.5%-16.5% is related to an effective number of parties of exactly 2.0, but can by no means be characterized as two-party competition (Gaines and Taagepera 2013;Dunleavy 2014). Appendix B2 (see Supplementary Material) shows how the assessment of Duvergerian outcomes, based on the effective number of parties, and alternative measures, overlap.…”

Section: Empirical Analysismentioning

confidence: 99%

Duverger and the territory: explaining deviations from the two-party-competition-law

Bochsler

2019

Journal of Elections, Public Opinion and Parties

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According to Duverger's Law, plurality voting systems lead to two-party competition. However, many results of national parliamentary elections deviate from this rule. In contrast to previous research, which argues that in countries with territorial splits, regional two-party systems aggregate to national multi-party systems, this article shows that this explanation accounts for only a small proportion of the empirical exceptions to Duverger's Law. Instead, this article distinguishes three explanations for Non-Duvergerian outcomes at the national level. The three mechanisms relate to the level of electoral constituencies, to the aggregation of constituency results, and to the interaction between constituency-and aggregation effects. This article assesses the explanatory power of each of the three explanations on an extensive sample of election results from plurality vote systems, linking national to constituency-level results.

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Section: Empirical Analysismentioning

confidence: 99%

Duverger and the territory: explaining deviations from the two-party-competition-law

Bochsler

2019

Journal of Elections, Public Opinion and Parties

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“…Dunleavy (2014) has quickly produced a lengthy "comment" alleging to demonstrate critical faults in each index, and urging others not to employ them in any future work. Here, we briefly explain why we find his critique unpersuasive.…”

Section: Introductionmentioning

confidence: 99%

“…Those who find these scores worrying, however, will, if they work through the whole of Dunleavy's comment, discover that how to interpret highly lopsided races of this sort is at the heart of our disagreement. Dunleavy (2014) opens with a general complaint that electoral analysis is "plagued" by poorly conceived indices, and lists six conditions for problems. This framework turns out to be irrelevant to the remainder of the piece, as all of the conditions are plainly vague and subjective.…”

Section: Introductionmentioning

confidence: 99%

More on Measuring Two-Party Competition: A Response to Dunleavy

Gaines

Taagepera

2014

Journal of Elections, Public Opinion and Parties

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Gaines and Taagepera [(2013) How to operationalize two-partyness. Journal of Elections Public Opinion and Parties, 23(4), pp. 387 -404] propose two indices of two-party competition for district-level data, both of which are alleged to be flawed. The case against them rests mainly on whether or not elections with one dominant party should be regarded as exhibiting one-or two-way competition. For those inclined to see 90 -10% and 50 -50% outcomes are different in kind, our indices can provide better measures than the popular effective number of parties or the "gap". We agree that assessment of a set of outcomes, in a given election or over time, requires careful attention to the important distinction between microlevel data and aggregate measures.

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Electoral rules and the two-party system: A methodological inquiry with reference to Duverger’s law

Golosov

2024

International Political Science Review

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The law of Duverger posits that the single-member plurality electoral system favours the two-party system. The empirical tests of Duvergerian effects often rely on the effective number of parties as the most common measure of party system fragmentation. This study, proceeding from the notion that more focused measures of two-partyness could be of greater utility for this purpose, examines the build-up of two already existing, albeit underused, indices that are intended to operationalize the concept of the two-party system and introduces a new family of party-system indices for the purpose of cross-validation. The quantitative analysis performed on simulated and real-life datasets shows that the measures of two-partyness can improve the methods of inquiry in research on Duvergerian effects, and that some of the indices introduced in this study can serve as useful supplements to the toolkit of political science.

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Neither the T Index nor the D₂ Score Measure “Two-Partyness”: A Comment on Gaines and Taagepera

Cited by 3 publications

References 11 publications

Duverger and the territory: explaining deviations from the two-party-competition-law

Duverger and the territory: explaining deviations from the two-party-competition-law

More on Measuring Two-Party Competition: A Response to Dunleavy

Electoral rules and the two-party system: A methodological inquiry with reference to Duverger’s law

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Neither the T Index nor the D2 Score Measure “Two-Partyness”: A Comment on Gaines and Taagepera

Cited by 3 publications

References 11 publications

Duverger and the territory: explaining deviations from the two-party-competition-law

Duverger and the territory: explaining deviations from the two-party-competition-law

More on Measuring Two-Party Competition: A Response to Dunleavy

Electoral rules and the two-party system: A methodological inquiry with reference to Duverger’s law

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Neither the T Index nor the D₂ Score Measure “Two-Partyness”: A Comment on Gaines and Taagepera