A Statistical Model for Party-Systems Analysis

Polarization is a key characteristic of party systems, but scholars disagree about how polarization relates to the number of parties in a system. Different authors find positive, negative, or null relationships. I claim that when polarization is measured using the weighted standard deviation of standardized party positions, seat-level polarization is equal to NS−112+NS−1, where NS is the effective number of seat-winning parties. This relationship is what one would expect if parties were drawn randomly from a super-population with an effective sample size somewhere between the effective and raw number of parties. I test this claim using multiple datasets which report party positions and seat shares, before extending my analysis to consider vote-level polarization, the range of positions, and polarization in presidential and parliamentary regimes. My work extends the Taageperaan research agenda of building interlocking networks of equations relating key quantities of electoral and party systems.

The present article follows up a previous study (Anckar 1998) which showed a strong association between size and party system fragmentation. The aim of the article is to see whether the explanatory power of size can, in fact, be attributed to a federal form of government. 77 countries with free party systems constitute the research population. The dependent variable has three components: number of parties, electoral support for the leading party, and the ‘effective number of parties’ calculated according to the Laakso‐Taagepera formula. Preliminary tests reveal that federal states have a more fragmented party system than unitary states. However, when controlling for size, electoral system, the ‘effective threshold,’ and presidentialism, the results clearly show that federalism is overshadowed by size and also, to a lesser extent, by the effective threshold.

Party systems, that is, the number and the size of all the parties within a country, can vary greatly across countries. I conduct a principal component analysis on a party seat share dataset of 17 advanced democracies from 1970 to 2013 to reduce the dimensionality of the data. I find that the most important dimensions that differentiate party systems are: “the size of the biggest two parties” and the level of “competition between the two biggest parties.” I use the results to compare the changes in electoral and legislative party systems. I also juxtapose the results to previous party system typologies and party system size measures. I find that typologies sort countries into categories based on variation along both dimensions. On the other hand, most of the current political science literature use measures (e.g., the effective number of parties) that are correlated with the first dimension. I suggest that instead of these, indices that measure the opposition structure and competition could be used to explore problems pertaining to the competitiveness of the party systems.

The aim of this paper is to explore and understand the Albanian Party System. The analysis will cover the period from the collapse of the communist regime in 1991 until 2014. It will try to investigate what forces drive the battle of the parties, what cleavages 'divide' society and consequently the party system as well as which are the parties that count the most. in order to assess this, the paper will focus on the parliamentary parties and will relay on various theoretical concepts of the contemporary literature on political parties. First it will draw on Sartori's concept of 'relevance' in order to understand whether all the parliamentary parties over the course of twenty four years of pluralism are important or not and what weight do they have. Then it will use the Laakso - Taagepera index of the Effective Number of Parties to understand how power is distributed within the parliament.

The purpose of the present article is to analyze the electoral returns of the Kazakhstani elections held in the 1995-2021 period to estimate both the static (such as frag-mentation) and the dynamic properties (fluidity) of the Kazakhstani party system. In addition to estimating the fragmentation and the instability of the party system resulting from parlia-mentary elections, the paper explores the relationship between the static properties of a party system, such as the level of party system fragmentation, and its dynamic properties, such as the level of fluidity of the party system. By doing so, the article reveals that the decrease in the level of fragmentation, measured on the basis of Rae’s index of fractionalization and Laakso and Taagepera’s Effective Number of Parties, was responsible for the growing insta-bility (fluidity) of the Kazakhstani party system.

The topic of electoral volatility was not at the center of academic work in Latin America until Scott Mainwaring and Timothy R. Scully’s seminal 1995 work Building Democratic Institutions: Party Systems in Latin America (cited in Electoral Volatility as an Expression of Party System Equilibrium). Preceding analyses primarily focused on explaining the breakdown of democratic politics in the region during the 1960s and 1970s. Conventional wisdom that departed from the classic work of Sartori in Parties and Party Systems (Cambridge, UK: Cambridge University Press, 1976), maintained that stable party systems are crucial for the durability of democracies, focusing his attention on aspects such as party system polarization and fragmentation. Mainwaring and Scully shift the discussion, arguing that previous literature on the region neglected and inadequately conceptualized an equally important property of party systems: their level of their institutionalization. According to Mainwaring and Scully, party system institutionalization (PSI) is formed by four different dimensions. The first is stability in the patterns of party competition. Thus, institutionalized party systems are those in which actors develop expectations, orientations, and behavior based on the premise that practices and organizations will prevail into the foreseeable future. Mainwaring’s 2018 work, Party Systems in Latin America (cited in Electoral Volatility as an Expression of Party System Equilibrium), argues that this is the only relevant dimension in PSI, while considering that the other three are just underpinnings that facilitate it. So according to this work, an institutionalized party system is the one in which a stable set of parties interacts regularly in stable ways. This stability of interparty competition is traditionally measured with the Pedersen volatility index, a comprehensive measure of the net systematic shift in levels of electoral support for parties across elections. As volatility is negatively correlated with this important dimension of party system institutionalization, conventional wisdom holds that political representation deteriorates when there is persistent high volatility. To this debate, the well-cited 2006 article by Mainwaring and Torcal, “Party System Institutionalization and Party System Theory after the Third Wave of Democratization” (cited in Electoral Volatility as an Expression of Party System Equilibrium), adds the idea that this lack of stability in the patterns of competition in party systems, measured by electoral volatility, is a typical characteristic of new and developing democracies. According to that study, the most important defining characteristic of party systems in less developed countries is captured by their lack of institutionalization, in other words, the amount of electoral volatility in their party systems. Since the publication of these three contributions, the debate on party system dynamics in the region has focused on cross-national levels of electoral volatility, their relationship with other indicators of party system stability, and their consequences for democratic quality and performance, while also broadening the analysis to Europe.

Quantitative Aspect of Parliamentary Elections in Serbia 2012–2023: Effective Number of Parties and Fragmentation of Party System

In this article, I explore the nature of party systems that have emerged in Africa in the wake of the adoption of democratic political systems after 1990. Although political parties help shape core democratic processes and institutions, parties and party systems have received relatively scant attention in the scholarly literature on democratization in Africa. I argue that party systems in most African countries are built on quite a different foundation from the one that undergirds both advanced industrial democracies and the theories about party systems generated by their experiences. I assess the strengths and limitations of the comparative literature on party system development in the light of African experiences, and argue for a more critical examination of concepts from that literature that have been widely used to assess the prospects and progress of party system institutionalization, including pluralism, system fragmentation and volatility.

This article overviews and seeks to explain the processes of party system formation in the post-Soviet Central Asian states (Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan) by focusing on a crucial party-system property, fragmentation. The analysis reveals that to a much greater extent than in democracies, where party systems are largely shaped by societal factors, the level of party system fragmentation in autocracies is determined by the scope of presidential powers, as entrenched in the formal institutional order and reflected in the national constitution. The level of authoritarianism is largely inconsequential for party system fragmentation, while the role of electoral rules is secondary. Institutionally weak and institutionally strong autocratic presidents have a preference for fragmented party systems, while presidents with an intermediate range of powers seek and obtain low levels of party system fragmentation.

Considerable evidence suggests that social diversity increases the number of political parties. While a vast literature examines this relationship by measuring social diversity as ethnic fragmentation, the convenience of capturing the level of social heterogeneity by using alternative indicators has been traditionally overlooked. In this article, I offer new evidence that documents the impact of social diversity on party system size by proxying the former as the number of social classes. Using both objective class positions and subjective class identifications and employing two different datasets that cover democratic legislative elections around the world between 1981 and 2015, I find that the effective number of social classes has a positive effect on party system fragmentation when the average district magnitude in a democracy is high. Given the difficulty to test these effects in a cross-country environment net of unobserved heterogeneity, I examine the robustness of the findings in Spain between 2000 and 2016, an ideal case due to large differences in district magnitude and a changing party system. Overall, the results suggest that high levels of social diversity are likely to increase party system fragmentation when the electoral system is permissive enough.

A randomization procedure is proposed to determine if sets of data used for phylogenetic analysis contain phylogenetically nonrandom information. The method compares the observed number of steps on a minimum length tree with the mean number of steps on minimum length trees derived from the same data set after character state assignments have been randomly permuted within each character. Such randomized data sets will exhibit exactly the same character state distributions as the original data but no phylogenetic information. In tests of 28 separate data sets using this procedure, the minimum lengths of each data set differed significantly from that expected for phylogenetically non-informative data in spite of the fact that observed consistency indices from the original data were as low as 0.230. The high correlation between number of steps per character on minimum length trees and number of taxa among the 28 original data sets is consistent with that expected if a more or less constant frequency of homoplasy occurs per character per taxon. This correlation implies that the consistency index may be an inappropriate, comparative measure of homoplasy among data sets. The observed pattern of increasing homoplasy with increasing numbers of taxa for the original data sets is curvilinear (when forced to pass through a fixed point for all data sets). This is qualitatively different from that expected for random data. Possible uses of the randomization techniques are suggested in cladistic studies using either compatibility analysis or parsimony.

Finding a new drug which is both safe and efficient is an expensive and time-consuming endeavour. In particular, establishing the ‘dose-effect relationship’ – how beneficial a drug is at different dosages – can be challenging. Predicting this curve requires gathering experimental data by exposing and recording how cells respond to various levels of the drug. However, extreme values are often observed at low and high dosages, potentially introducing errors that are hard to correct in the prediction process. Yet, these extreme observations are sometimes genuine so researchers cannot just ignore them. To improve dose-effect estimation, Zhou, Liu, Fang et al. developed a new general-purpose approach. It uses advanced statistical modelling to account for extremes in lab data. This strategy outperformed other methods when dealing with these observations while also providing higher efficiency in data analysis with more uniform data in experiments. To facilitate implementation, Zhou, Liu, Fang et al. set up a user-friendly tool baptized ‘REAP’; this free online resource allows scientists without advanced statistical experience to harness the new approach and to perform dose-effect analysis more easily and accurately. This could boost research across many different disciplines that examine the effects of chemicals on cells.

Prior to the 2002 electoral reform, political parties in Russia’s regional legislative elections showed poor performance. Since December 2003, however, all regions have been obliged to elect no less than half of the members of their assemblies by proportional representation. As a result, party competition at the sub-national level became unavoidable. This study tests three kinds of hypotheses dealing with the institutional, sociological, and political factors in the fragmentation of party systems within Russia’s regions. The analysis demonstrates that political factors, especially the activity of the Kremlin and the heads of regional executives, have played the primary role in shaping regional party systems.

A new theoretical development for examining the institutionalization of party systems is proposed in this article. We build on electoral coordination theories to disaggregate volatility into the vote transfers that occur between or towards parties that are in equilibrium (which we call endogenous volatility) and those that are not (exogenous volatility). The former captures accountability, and the latter reflects the number of voters who are not acting in accordance with the existing equilibrium in the party system. Exogenous volatility measures the institutionalization of party systems. We also show that endogenous volatility depends on government performance, while exogenous volatility is a function of institutional openness. The empirical evidence comes from an original data set that includes 448 electoral cycles in lower-house elections in 66 countries between 1977 and 2011.

Legislative policy-making authority, party system size, and party system nationalization