Electoral systems and income inequality: a tale of political equality

Zuazu, Izaskun Article — Published Version Electoral systems and income inequality: a tale of political equality Empirical Economics Provided in Cooperation with: Springer Nature Suggested Citation: Zuazu, Izaskun (2021) : Electoral systems and income inequality: a tale of political equality, Empirical Economics, ISSN 1435-8921, Springer, Berlin, Heidelberg, Vol. 63, Iss. 2, pp. 793-819, https://doi.org/10.1007/s00181-021-02154-9 This Version is available at: https://hdl.handle.net/10419/286753 Standard-Nutzungsbedingungen: Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. 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If the documents have been made available under an Open Content Licence (especially Creative Commons Licences), you may exercise further usage rights as specified in the indicated licence. https://creativecommons.org/licenses/by/4.0/ Empirical Economics (2022) 63:793–819 https://doi.org/10.1007/s00181-021-02154-9 Electoral systems and income inequality: a tale of political equality Izaskun Zuazu1 Received: 11 October 2020 / Accepted: 30 September 2021 / Published online: 21 October 2021 © The Author(s) 2021 Abstract The link between democracy and within-country income inequality remains an unresolved quest in the literature of political economy. To look into this debate, I propose exploring the implications of electoral systems, rather than political regimes, on income inequality. I surmise that proportional representation systems should be associated with lower income inequality than majoritarian or mixed systems. Further, I conjecture that the relationship between electoral systems and income inequality hinges on the de facto distribution of real political power, namely political equality. I use data on 85 countries covering the period 1960–2016 and specify models able to capture the persistence and mean reversion of income inequality. The estimates fail to significantly associate democracy with income inequality, and find other political institutions to significantly shape income inequality. The paper finds a robust association between more proportional systems and lower income inequality. However, this association depends on political equality. Changes towards proportional representation systems seem to lower income inequality at low and medium levels of political equality. Strikingly, instrumental variable estimates show that changes in electoral systems in political equal societies increases income inequality. Keywords Political equality ·Income inequality ·Proportional representation systems ·Panel data JEL classifications D63 ·D72 ·C23 1 Introduction Economic inequality has experienced a remarkable increase since the 1970s in virtually all Western democracies (Piketty 2014; Atkinson 2015). Along with the current rise of BIzaskun Zuazu [email protected]; [email protected] 1Institute for Socio-Economics, University of Duisburg-Essen, Duisburg, Germany 123 794 I. Zuazu wealth inequality, a challenging feature emerges from the data on income inequality. Today’s pattern of economic inequality is largely shaped by an increasingly polarised distribution of incomes and the persistence of intergenerational inequalities. Income inequality of such a nature has crucial socio-economic implications, ranging from reducing economic sustainability to unleashing more rigid social hierarchies, and establishing features typical of a feudal society (Franzini and Pianta 2015). These rising trends of income inequality in democracies are at odds with the predictions of the commonly used model in existing political economy literature, the so-called medianvoter model (Meltzer and Richard 1981). That model argues that democratisation should lead to the implementation of pro-poor policies and ultimately reduce inequality. However, what we see in real world economics is quite the opposite. Why do we see rising levels of income inequality in established democracies then? Empirical literature on the link between democracy and income inequality is still full of contradictory results (Acemoglu et al. 2015). Democracy is indeed associated with either increasing or decreasing income inequality, findings that vary depending on country and time coverage in the datasets, estimation techniques or measures of democracy (Krauss 2016). Along these lines, recent literature suggests that democracy in itself might not warrant institutional or economic improvements (Chong and Gradstein 2019; Wong 2021; Bahamonde and Trasberg 2021). Hence, analysing the inequality effect of other institutional changes beyond democracy seems worth considering. The current paper empirically tests two main hypotheses. Firstly, it distinguishes countries on the basis of other de jure political features such as electoral systems— rather than political regimes (i.e. democracy)—to shed some light on the existing conflicting results in democracy-inequality literature. Electoral systems are formal institutions that translate votes into seats in parliaments on the basis of different rules and result in varying degrees of political representation of societal groups. There is an array of potential channels, as further discussed in the paper, that might induce alternative distributive effects of electoral systems. Hence, the paper first tests whether electoral systems translate into different levels of within-country income inequality. Secondly, the paper hypothesises that the inequality impact of electoral systems depends on de facto distribution of real political power, namely political equality. Democracy and political equality are highly related but distinct concepts. The differentiation boils down to the formal or de jure essence of the conceptualisation of democracy as a political regime, and the informal or de facto nature of political equality, which is borne out in actual human interaction (Voigt 2013). Hence, political equality refers to the extent to which real political power is evenly distributed across socio-economic groups by means of similar participation in civil society organisations, voter turnout, and ability to implement and monitor the political agenda. The way in which democracy is defined and measured focuses on the characterisation of political regimes, rather than how citizens exercise their political will.1Indeed, 1Consider for instance the definition in Boix et al. (2013), a well-known and extensively used measure of democracy. A country is considered democratic if it satisfies conditions for both contestation (i) ‘The executive is directly or indirectly elected in popular elections and is responsible either directly to voters or to a legislature’; (ii) ‘the legislature (or the executive if elected directly) is chosen in free and fair elections’, and participation (iii) ‘a majority of adult men has the right to vote.’ In this definition, women are excluded in the consideration of what a democracy is. 123 Electoral systems and income inequality: a tale of… 795 although democracies hold higher levels of political equality than non-democracies, there is substantial variation in levels of political equality within democratic regimes (Houle 2018). The demand for data on political equality dates back to Verba and Orren (1985), and the present paper benefits from the availability nowadays of quantitative methods and data coverage (Bartels 2017; Pemstein et al. 2015; Houle 2018). Disentangling the effects of de jure and de facto conceptualisations of democratic politics might ultimately provide a better insight into the link between democracy and inequality, as extant literature has done regarding the link between political institutions and economic growth (Spruk 2016; Hartmann and Spruk 2020). Using a database with information on 85 countries covering the period 1960–2016, I tested whether electoral systems and their interplay with political equality are associated with within-country income inequality. I specified static and dynamic panel data models and used annual and non-overlapping 5-year and 10-year periods that include a variety of empirically-informed drivers of income inequality. The results can be summarised as follows: (i) Estimates point to more proportional parliaments as potential deterrents of income inequality. (ii) This relationship depends inversely on the level of political equality. The interaction between electoral systems and political equality is found to be significant, by which electoral systems reduce income inequality at low or median levels of political equality. In highly political equal societies, changes towards more proportional electoral systems can rise income inequality. (iii) Estimates do not significantly associate democracy with income inequality, although it seems that the age of a democracy might play a marginal role. The remainder of the text is structured as follows. Section 2reviews the literature and provides the main theoretical arguments of the hypothesis. Section 3explains the data, the econometric models, and main results. Section 4concludes. 2 Democracy and income inequality: an on-going puzzle At first glance, democratic regimes might be expected to be more likely to implement inequality-correcting policies and should thus be associated with lower levels of income inequality.2Against this posit, current trends show that democratic governments coexist quite callously with rising levels of income inequality. Yet empirical economics literature on democracy and inequality seems far from reaching a consensus, as they associates democracy with either a negligible or increasing effect on income inequality (Dreher and Gaston 2008; Scheve and Stasavage 2009; Acemoglu et al. 2015). Figure 1employs data on the sample of countries used in the econometric analysis below to plot the correlation between pre-tax income inequality (y-axis), measured with the pre-tax Gini index collected from the Standardized World Income Inequality 2Theoretical and empirical challenges of the workhorse model of democracy-inequality literature (Meltzer and Richard 1981) are for instances Benabou (2000) and Milanovic (2000). See Midtbø (2018) for a recent test using individual data and Bayesian methods. 123 796 I. Zuazu Fig. 1 Correlation between democracy and income inequality, by population size Fig. 2 Evolution of pre-tax and post-tax gini indices in democracies and non-democracies Database (SWIID), and democracy (x-axis), measured with the Polity2 index of the Polity IV Project (Marshall et al. 2017). Although Gini indices satisfy the criteria for comparing income distributions across countries and over time irrespectively of their population size or their aggregate income (Cowell 2000), it is interesting to consider a human welfare perspective of income distribution across countries (Sala-i Martin 2006). To visually account for that, the size of the dots in Fig. 1is proportional to the sample countries’ population size, where the biggest dot corresponds to India. The correlation between democracy and income inequality seems to be weak and slightly positive. Figure 2shows the evolution of both pre-tax and post-tax Gini indices in democratic and non-democratic countries in the sample. Democracies show on average an increasing trend in income inequality and a reduction of redistribution during the whole period considered (1970–2016), although there is a reducing post-tax income inequal- 123 Electoral systems and income inequality: a tale of… 797 ity trend in the turn of the 20th century. Non-democracies show reducing levels of income inequality, both in terms of pre-market and post-market inequality. Among the reasons behind rising pre-tax and post-tax income inequality in democracies, the literature highlights firstly, that voters’ political preferences go beyond income distribution issues (Roemer 2009), secondly, that powerful elites might capture democratic institutions to distort the implementation of pro-poor policies (Larcinese 2011;Berlinskietal. 2011; Acemoglu et al. 2013), thirdly, that democracy unleashes inequality-enhancing structural changes (Bergh 2005; Acemoglu et al. 2015), and fourthly, a biased middle class that does not pursue equalising policies (Aidt et al. 2010; Besley et al. 2010; Acemoglu et al. 2015). In either of these four propositions, the link between democracy and inequality ambiguously depends on specific features, such as the interplay between de jure and de facto political power distribution, the structural transformation of the economy and the distance between the median and mean voter’s preferences of the level of redistribution and types of public policies. 2.1 Proportionality of parliaments and income inequality This paper studies whether and how electoral systems affect income inequality. Electoral systems crucially channel voters’ preferences to the policies implemented by the government, and are divided into proportional representation (PR, henceforth) systems (used in countries like Israel or Spain), majoritarian systems (United States, United Kingdom, France or Canada) and mixed systems (Germany, New Zealand or Hungary).3 Constitutional political economy literature provides stylised facts about how the choice of electoral system affects the economy at large, and income inequality and redistribution in particular. Electoral systems are primary able to encourage or discourage strategic voting behaviour (Boix 1999), where majoritarian systems enforce voter coordination and second-ranked political platforms. To the contrary, PR systems provide less incentives to vote strategically because seats in parliaments under that rules can be gained with only a fraction of the total vote, and thus, allowing voters to pursue their preferred political platforms. Majoritarian rules conduce to unstable policy choices Cox and McCubbins (1994), whereas PR systems, characterized by higher propensity of form coalitions in governments, provide higher levels of institutional stability. More consensual and stable policy-making can favour the reduction of income inequality. Other channels in which electoral systems can unleash distributional effects are through geographic concentration and the magnitude of districts (Rickard 2012) and the strength of lobbying activities (Naoi and Krauss 2009). Electoral systems can also influence income inequality levels on the basis of international trade-oriented (Kono 2009), the political representation of minorities (Norris et al. 2004), and the political ideology of governments (Iversen and Soskice 2006). This body of research speaks to the sensitivity of governments to cater to different groups in the electorate, which may in turn lead to different levels of income inequality. Overall, the evidence tends to show that PR systems have greater redistribution and 3See Herron et al. (2018) and Bormann and Golder (2013) for a characterisation and explanation of electoral systems. 123 798 I. Zuazu public spending than majoritarian systems (Persson and Tabellini 2004; Lizzeri and Persico 2001). Along these lines, this paper argues that the relative greater social spending and public policies associated with more proportionality in parliaments may unleash further distributional effects. Alternative electoral systems are associated with different social provisioning of education, health and inequality-correcting policies that levelling up the demand-side factors of the labor market Persson et al. (2007), Lizzeri and Persico (2001), and therefore, pre-market income inequality can be reduced or increased under alternative systems. The current paper makes a crucial distinction between the effects of electoral systems in income inequality and redistribution. PR systems are usually associated with both higher public spending, which can be related more easily with political platforms aiming at reducing pre-tax income inequality, and redistribution, that ca be more attributable to post-tax income inequality. It should be noted that the choice of electoral systems are also influenced by economic and income inequality factors. A change of the electoral system can occur as a threat of opposition from the electorate (Boix 1999; Chang and Higashijima 2021), implying a two-way causal link between the choice of electoral systems and levels of income inequality and redistribution.4 Generally, pre-tax income inequality can be less visible to the electorate, implying a weaker link between income inequality and change of electoral systems than in the case of post-tax income inequality. Based on these stylized facts of previous works in the reference literature, the key argument in the current paper is that changes towards more proportional parliaments should be associated with lower income inequality. Higher proportionality in parliaments reflects a higher consistency between votes and seats, which allow demands for inequality-reducing policies and general interest public spending programs (e.g. education, health, social security) to gain political representation. This might ultimately lead to reducing income inequality. Pre-tax income distribution might be crucially influenced by the welfare state in general, and by the electoral system, in particular. The intergenerational distribution of income, the labour supply and the feedback behavioural effects of tax and transfers in the workforce, and through levelling the playing field of public policies such as education (Bergh 2005), are among the channels through which electoral systems can affect pre-tax income inequality. The right plot in Fig. 3gives a hint of the different pre-tax and post-tax income inequality levels in PR systems and non-PR systems (majoritarian systems and mixed systems) during the period under scrutiny. The sample countries under proportional rules show on average higher levels of pre-tax Gini index, although there is a convergence between PR and non-PR countries in recent years.5Taking into account post-tax Gini indices, there is a similar evolution of both groups of countries. More importantly, the figure shows that PR systems generally redistributed more, that is, the difference 4To alleviate the reverse causality issue in the empirical analysis below, I focus exclusively on the effect of electoral systems in pre-tax income inequality. 5One may be concerned about the presence of PR systems in non-democracies and non-PR systems in democracies. It should be noted that the sample shows a balance distribution of electoral systems by political regime types, by which one third of non-democracies use proportional rules, and around half of the sample democracies use proportional rules. 123 Electoral systems and income inequality: a tale of… 799 Fig. 3 Evolution of pre-tax and post-tax gini indices in PR and non-PR countries between pre-tax and post-tax Gini indices is on average greater in PR systems than in non-proportional systems. Existing works on the precise link of electoral systems in income inequality are scarce, and are summarised here. Theoretically, Austen-Smith (2000) observes that PR systems, usually characterised by more than two parties, exhibit higher tax rates and flatter income distribution than the typical two-party majoritarian electoral systems. Empirical research on these mechanisms tends to associate more proportional electoral systems with lower levels of within-country income inequality. Verardi (2005) focuses on the effect of district magnitude in electoral systems on income inequality. Using data on 28 countries and a 4-year time span, he finds that when the degree of proportionality increases, income inequality decreases. Along similar lines, Birchfield and Crepaz (1998) consider the larger number of effective parties under PR than in majoritarian systems to study the link between electoral systems and income inequality. Using data on 18 countries at two points in time, they find that PR systems (majoritarian systems) are associated with lower (higher) income inequality. Nevertheless, the literature calls for the use of more extensive databases as well as more computational demanding techniques and specifications, to provide sound empirical leverage to the link between electoral systems and income inequality. 2.2 De jure and de facto political institutions Previous literature distinguishes the economic aftermath of de jure and de facto institutions, and shows the complementarity of both types of institutions to set the rules and enforcing the mechanisms to create economic prosperity. Empirical evidence shows that yet de jure and de facto judiciary institutions are correlated with economic growth, it seems that the latter play a more relevant role in enhancing development (Voigt et al. 123 800 I. Zuazu 2015; Marciano et al. 2019). Directly related to the current paper, Spruk (2016) constructs latent de jure and de facto measures of political institutions to find a persistent impact of the latter in long-run development. Further, Hartmann and Spruk (2020) provide evidence on that both de jure and de facto institutional instability are important deterrents of income and growth. This body of literature confirms the primacy of de facto over de jure political institutions in driving economic development. The present paper adds to this literature by focusing at the effect of de jure and de facto political institutions in income inequality. The second hypothesis of this paper is that the effect of electoral systems in income inequality hinges on political equality. Hence, I consider the interplay between de jure and de facto political institutions to impact on income inequality. Theoretically, I draw on the model in Acemoglu and Robinson (2008) that shows how changes in de jure political institutions might be offset by de facto political institutions, thus perpetuating equilibrium outcomes. I applied the model provided by Acemoglu and Robinson (2008) to the case of changes in electoral systems that distribute more de jure political power to the masses (e.g. more proportional systems). The final economic outcome of those changes, authors suggest, might depend on the de facto power of a political elite to distort the political process in their favour. As a result, inequalityreducing de jure political changes may be countervailed by low levels of political equality, thus perpetuating income inequality. Changes in electoral systems, as de jure institutional changes, and their interplay with political equality, as a de facto political institution, are indeed a perfect platform to test the theoretical model in Acemoglu and Robinson (2008). The next section empirically tests whether changes in de jure political institutions and their interplay with de facto institutions affects income inequality. Nonetheless, it should be noted that previous research has also focused on the reverse mechanism, i.e. income inequality as a causal determinant of political equality (Solt 2008; Houle 2018). Notwithstanding the econometric techniques employed here to circumvent reverse causality issues, the reader should feel free to interpret the results as partial correlations. Recalling the critique in Krauss (2016) on the limits of inferring causal mechanisms in macro-level frameworks, the modest goal of the current paper is to look at the role of political institutions in income inequality in a manner that existing literature has not yet explored in detail. In any case, the empirical approach taken in the current paper supplements previous research on the electoral systems-income inequality link (Birchfield and Crepaz 1998; Verardi 2005) in its specific aspect, and aims to contribute to the debate on democracy-income inequality in general by considering more nuanced conceptualisations of political institutions. 3 Empirical analysis This paper tests whether electoral systems are related with within-country income inequality, and whether this relationship hinges upon the distribution of political power across socio-economic groups of the population. This section describes the data employed, the econometric specifications and the main results. I link data on income inequality with information on electoral systems and political equality, along 123 Electoral systems and income inequality: a tale of… 807 Table 1 continued (1) (2) (3) (4) (5) (6) (7) WG WG WG WG WG WG Sys-GMM Annual 5years 10years Annual 5years 10years Annual No. of Groups 85 85 85 85 85 85 85 Within R-squared 0.435 0.408 0.398 0.977 0.979 0.985 No. of Instruments 17 AR(1) 0.000 AR(2) 0.167 Hansen J 0.191 Diff-Hansen 0.708 Columns (1–6) provide estimates of fixed-effects within regression models with Driscoll–Kraay standard errors Columns 7 provides a dynamic panel data model estimated with system-GMM All models include full set of controls as in Column 7 Table 6and time fixed effects Annual data, 5-years or 10-years non-overlapping periods from 1960 to 2016 Driscoll–Kraay standard errors in parentheses (Columns 1–6) Country and year clustered standard errors in parentheses (Column 7) ∗(p<0.1),∗∗(p<0.05), ∗∗∗(p<0.01) 123 808 I. Zuazu Fig. 4 Effect of PR by political equality (system-GMM estimates) models that use annual data (Columns 1 and 7, Table 1). As a further robustness check, I conducted population-weighted additional models which show similar results to the main findings (see Table S1 in the online supplementary material). Columns 4–7 (Table 1) include lags of the dependent variable, and use either annual (1960–2016), 5-year or 10-year non-overlapping periods (1960–2016). The lagged pre-tax Gini index is associated with an increasing effect in current income inequality. The presence of the lagged dependent variable biases within-group estimates. Thus, I apply the system-GMM to the model in Eq. 1in Column 7 (Table 1). Instrumental variables results provide further leverage of the inequality effect of electoral systems: PR is associated with a negative and significant role in income inequality, political equality is also negatively associated with inequality, and the interaction is positive and statistically significant. Figure 4represents the average marginal effect estimated in Column 7 (Table 1)on the pre-tax Gini index for changes in electoral systems to PR in t−1 by different levels of political equality, while showing a histogram of the distribution of real political power in the sample.14 The interactive model specified in Eq. 1assumes that the effect of PR varies at different levels of political equality and, thus, the final effect might consider the interaction, provided it is significant, times the level of political equality.15 PR is associated with reducing income inequality at low and medium levels of political equality. As societies become more politically equal, the inequality-reducing effect of changes in electoral system reduces in magnitude. Table 2provides a closer look at the marginal effects of electoral systems on income inequality at different levels of political equality. Considering the average marginal effects of lagged PR on income inequality with clustered standard errors at country and time levels, we find that, beyond a level of 0.8 for political equality, changes in electoral systems are associated with increasing income inequality. The point estimates imply 14 Using 5-year and 10-year non-overlapping periods, system-GMM estimator yields similar results. 15 That is, the partial derivative of Eq. 1with respect to PRc,t−1;δ(Yct ) δ(PRc,t−1)=β1+β3∗PEc,t−1. 123 Electoral systems and income inequality: a tale of… 809 Table 2 Average marginal effects of PR on pre-tax gini index at different levels of political equality Political equality dy/dxClustered S.E. zpvalue 0−0.023 0.004 −5.52 0.000 0.25 −0.016 0.003 −5.56 0.000 0.50 −0.008 0.005 −5.57 0.000 0.75 −0.001 0.001 −1.69 0.091 10.006 0.001 4.42 0.000 Marginal estimates of system-GMM model (Column 7, Table 1) that, when there is a monopoly of political power (PE =0), a change to PR in the previous period decreases income inequality in the current period by about 0.02 point of the pre-tax Gini coefficient (at a significance level of 1%). For values of political equality around 0.25 and 0.5 (PE =0.5), the same change in electoral system will reduce the pre-tax Gini index by 0.16 and 0.01 points (at a significance level of 1%). For countries with a level of political equality of over 0.75, changes in the electoral system are associated with a reducing effect in the pre-tax Gini index of 0.001 at 10% of significance, whereas for highly political equal countries (PE =1), changes to PR systems increases pre-tax income inequality by 0.01 points of Gini coefficient. The estimates indicate that in political unequal societies, such as the case of Ukraine (2000–2003), Argentina (1977–1982), Chile (1977–1987) and the Philippines (1971), changes to PR seem to reduce income inequality. However, the results tend to suggest that in more politically equal societies, such as Madagascar (1999–2006) or Romania (2007–2013), changes to PR are also associated with a reducing effect on income inequality, although to a lesser extent. Lastly, in societies with even distributions of real political power (New Zealand, Finland, Sweden, among others), the role of electoral systems in income inequality does not seem significant. One mechanism behind the above results might be that voters are divided beyond economic inequality (Roemer 2009; Scheve and Stasavage 2017), and this argument may play a stronger role for those societies with even distributions of real political power. The estimates suggest that when more political representation is granted to minority groups in unequal societies, there is a mechanism by which income inequality can be reduced. However, this does not seem to apply when there is a greater de jure representation of minorities in politically equal societies. A potential explanation for the different ways that electoral changes affect income inequality, depending on the distribution of political power, might reflect different political demands of minority groups in low, median and highly political equal societies. A further consideration of this explanation requires knowing the kind of political demands of newly represented groups in parliaments and their preferences over inequality-correcting policies, an exercise that I leave for future research. Other potential mechanisms at work in the inequality-increasing effect of more proportionality in political equal societies go along new evidence on the link between democratic rule and income inequality. Recent contributions to the literature suggest that higher inclusiveness in the political process, while keeping contestation equal (Wong 2021), and high state capacity (Bahamonde and Trasberg 2021), can increase 123 810 I. Zuazu within-country income inequality through repetitively, political capture by elites and alienation of marginalized groups, and financial development. Consistent with previous literature de jure and de facto political institutions (Voigt et al. 2015; Spruk 2016; Hartmann and Spruk 2020), the estimates imply differentiated economic effects of both types of institutions. More precisely, the estimates speak to the increasing political stability of more proportional systems (Cox and McCubbins 1994) and de jure and de facto political institutions (Hartmann and Spruk 2020), such as electoral systems and political equality, in producing varying levels of within-country income inequality. Finally, similarly to Spruk (2016), I find different absolute magnitudes of the economic effects of de jure and de facto political institutions. However, based on the instrumentalist variable estimates, the role of electoral systems (as de jure political institution) is greater than that of political equality (as de facto political institution) in within-country income inequality.16 4 Conclusion The starting point for this paper was the observation of rising within-country income inequality in established democracies. In theory, democratic governments should be able to correct for rising inequality through the processes of enfranchisement and political competition. In practice, democratic governments have coexisted and been callously indifferent about rising levels of income inequality over the last few decades. This paper aims to advance our understanding of the link between democracy and inequality by approaching the issue from an alternative perspective. Using a conceptualisation of democratic political institutions that differentiates between de jure and de facto political institutions, I argue that de jure politico-institutional changes that might, in principle, lower inequality can be countervailed by de facto political power. Specifically, the paper surmises two hypotheses. Firstly, electoral systems, which are used to translate votes into seats on a different basis, have an effect on income inequality. Secondly, I argue that this effect is contingent upon political equality in the country. I construct an extensive database, linking data on income inequality and political institutions, that supplements previous research in terms of time and country coverage, with the inclusion of empirically informed drivers of inequality. I specify static and dynamic panel data models, use alternative estimation techniques, and use either annual data or 5-year and 10-year non-overlapping periods. The results significantly associate proportional representation systems with lower income inequality. The results also find that the impact of electoral systems on inequality is contingent on the distribution of political power in society. More precisely, instrumental variable estimates show that at low and median levels of political equality, changes towards proportional representation systems reduce income inequality, and the magnitude of the effect reduces as societies become more politically equal. Strikingly, in highly political equal societies, changes towards more proportional electoral systems are associated with rising income inequality. The estimates include a variety of controls, in which importantly, none of the alternative measures of democracy is significantly 16 The coefficients associated with PR and PE are respectively −0.023 and −0.01 (Column 7, Table 1). 123 Electoral systems and income inequality: a tale of… 811 associated with income inequality. The estimates robustly support the N-shape relationship between economic development and income inequality found in Lessmann and Seidel (2017). These findings add new evidence on the workings of the political institutional settings in producing within-country income distribution. The paper shows that increasing proportionality in politically unequal societies is associated with lower pre-tax Gini coefficients, whereas the same changes in politically equal societies seem to be unrelated to income inequality. The interpretation of these results might follow along the lines of Roemer (2009), who argued that voters’ preferences might be unrelated to or go beyond economic inequality issues. The results here suggest that this reasoning might specifically apply to politically equal societies. Additionally, the above estimates breathe new life in our understanding of the economic effects of de jure and de facto political institutions. Along the lines of Spruk (2016) and Hartmann and Spruk (2020), the current paper finds that both electoral systems (de jure) and political equality (de facto) play different roles in the economy, and that both should be accounted for in regression models. All in all, the findings of this paper might help to identify in which type of societies changes in electoral systems might lead to reducing income inequality. At the same time, the paper shows how more nuanced conceptualisations of political institutions, such as the de jure versus de facto characterisations, might allow a better understanding of the political causes of income distribution. Nonetheless, there are several questions still to be answered related to the mechanisms behind the above findings. Two natural extensions of the current paper emerge. Exploring how the political stability of both de jure and de facto political institutions intertwine with income distribution would provide a better knowledge of the political-institutional underpinning of income inequality. Additionally, future research on the interplay between electoral systems, political equality and inequality should consider micro-level approaches with information on the political demands of minority and newly enfranchised groups. Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/s00181-021-02154-9. Acknowledgements Earlier versions of this paper were presented at the 1st Conference of the Catalan Economic Society (CES), Barcelona, Spain (2017), 21st Annual Conference of the Society for Institutional & Organizational Economics (SIOE), Columbia University, New-York, USA (2017), and 31st Annual Meeting European Association for Evolutionary Political Economy (EAEPE), Warsaw School of Economics, Poland (2019). I would like to thank Adam Przeworski, Steven Stillman and Jakob Kapeller for helpful comments. The research received funding from the Spanish State Research Agency and the European Regional Development Fund ECO2016-76884-P, and by the Ph.D. scholarship of the Spanish Ministry of Economy and Competitiveness (MINECO). Funding Open Access funding enabled and organized by Projekt DEAL. Declarations Conflict of interest There is no conflict of interest in this research. 123 812 I. Zuazu Ethical approval This article does not contain any studies with human participants performed by any of the authors. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Appendix Dataset for replication and codes are available from the author upon request at izzuazu(at)gmail.com or [email protected] List of countries: Argentina, Armenia, Australia, Austria, Bangladesh, Barbados, Belgium, Benin, Bolivia, Brazil, Bulgaria, Burundi, Canada, Chile, Colombia, Costa Rica, Czech Republic, Denmark, Dominican Republic, Ecuador, El Salvador, Estonia, Fiji, Finland, France, Georgia, Germany, Ghana, Greece, Guatemala, Honduras, Hungary, Iceland, India, Ireland, Israel, Italy, Jamaica, Japan, Kenya, Korea, Kyrgyzstan, Latvia, Lebanon, Liberia, Lithuania, Madagascar, Malawi, Mali, Mauritania, Mauritius, Mexico, Moldova, Myanmar, Nepal, Netherlands, New Zealand, Nicaragua, Niger, Nigeria, Norway, Pakistan, Panama, Paraguay, Peru, Philippines, Poland, Portugal,Romania, Senegal, Sierra Leone,Slovakia,Spain, Sri Lanka, Sweden,Switzerland, Thailand, Trinidad and Tobago, Turkey, Uganda, Ukraine, United Kingdom, United States, Uruguay, Venezuela 123 Electoral systems and income inequality: a tale of… 813 Table 3 Changes in electoral system in database Country From To Year Country From To Year Argentina MR PR 1963 Madagascar PR MS 1998 France MR PR 1986 Philippines MR MS 1998 Turkey PR MS 1987 Ukraine MR MS 1998 France PR MR 1988 Thailand MR MS 2001 Korea MR MS 1988 Sierra Leone PR MR 2002 Panama PR MS 1989 Ecuador MS PR 2002 Sri Lanka MR PR 1989 Italy MS PR 2006 Venezuela PR MS 1993 Ukraine MS PR 2006 Paraguay MS PR 1993 Greece PR MS 2007 Italy PR MS 1994 Madagascar MS MR 2007 Turkey MS PR 1995 Romania PR MS 2008 Sierra Leone MR PR 1996 Bulgaria PR MS 2009 Japan MR MS 1996 Ukraine PR MS 2012 New Zealand MR MS 1996 Greece MS PR 2012 Bolivia PR MS 1997 Bulgaria MS PR 2013 Ecuador PR MS 1998 Romania MS PR 2016 Table 4 Cross-correlation of political institutions Variables PR Political equality Democracy (Boix) Polity 2 Political equality 0.180 Democracy (Boix) 0.192 0.439 Polity 2 0.181 0.495 0.861 Age of democracy 0.020 0.184 −0.167 0.030 123 814 I. Zuazu Table 5 Summary statistics Variable Obs Mean SD Min Max Pre-tax Gini Index 2567 0.448 .0057 0.215 0.604 PR 2567 0.534 0.499 0 1 Political equality 2567 0.639 0.208 0 1 GDP pc (log) 2566 8.911 1.492 5.391 11.425 Elderly ratio 2513 9.372 5.263 2.175 26.015 Education 2567 8.434 3.061 0.868 13.61 Urbanization 2567 62.044 21.142 7.01 97.92 KOF 2513 62.261 15.485 23.29 90.67 FDI 2499 3.153 5.59 −28.62 87.44 Polity2 2508 7.068 4.545 −910 Democracy 2513 0.846 0.361 0 1 Age of democracy 2513 41.78 43.693 1 216 Union density 1033 33.696 21.542 4.4 98.7 Based on column 7 (Table 1) 123 Electoral systems and income inequality: a tale of… 815 Table 6 Within-group estimates and selection of controls (1) (2) (3) (4) (5) (6) (7) (8) Dependent variable: pre-tax gini index (SWIID Gini market) L.PR 0.007 −0.011 −0.020 −0.019∗−0.020∗−0.020∗−0.019∗−0.050∗∗ (0.004) (0.017) (0.015) (0.011) (0.011) (0.011) (0.011) (0.022) L.PE −0.043∗∗ −0.070∗∗∗ −0.058∗∗ −0.039∗−0.039∗−0.037∗−0.037∗−0.115∗∗∗ (0.021) (0.026) (0.023) (0.020) (0.020) (0.021) (0.021) (0.031) L.PR*PE 0.031 0.043 0.034∗0.037∗0.036∗0.034∗0.098∗∗∗ (0.027) (0.026) (0.019) (0.020) (0.020) (0.019) (0.034) L.GDP pc (log) 0.675∗∗∗ 0.837∗∗∗ 0.799∗∗∗ 0.827∗∗∗ 0.812∗∗∗ 0.647 (0.241) (0.242) (0.245) (0.240) (0.235) (0.500) L.GDP pc (log)2−0.085∗∗∗ −0.104∗∗∗ −0.099∗∗∗ −0.103∗∗∗ −0.101∗∗∗ −0.079 (0.028) (0.029) (0.029) (0.029) (0.028) (0.060) L.GDP pc (log)30.004∗∗∗ 0.004∗∗∗ 0.004∗∗∗ 0.004∗∗∗ 0.004∗∗∗ 0.003 (0.001) (0.001) (0.001) (0.001) (0.001) (0.002) L.Elderly 0.005∗∗∗ 0.005∗∗∗ 0.004∗∗∗ 0.004∗∗∗ 0.001 (0.001) (0.001) (0.001) (0.001) (0.002) L.Education −0.010 −0.009 −0.008 −0.008 0.005 (0.006) (0.006) (0.006) (0.006) (0.013) 123 816 I. Zuazu Table 6 continued (1) (2) (3) (4) (5) (6) (7) (8) L.Urbanization −0.001 −0.001 −0.001 −0.001 −0.001∗ (0.001) (0.001) (0.001) (0.001) (0.001) L.KOF 0.000 0.000 0.000 0.000 0.001 (0.001) (0.001) (0.001) (0.001) (0.001) L.FDI −0.000 −0.000 −0.000 −0.000 0.000 (0.000) (0.000) (0.000) (0.000) (0.000) L.Polity2 −0.001 −0.000 (0.000) (0.000) L.Democracy −0.004 (0.004) L.Age democracy 0.000∗∗∗ 0.000 (0.000) (0.001) L.Union density −0.000 (0.000) Constant 0.465∗∗∗ 0.475∗∗∗ −1.237∗−1.686∗∗ −1.578∗∗ −1.663∗∗ −1.631∗∗ −1.131 (0.026) (0.027) (0.691) (0.685) (0.690) (0.682) (0.666) (1.404) Controls No No No Yes Yes Yes Yes Yes Time FE Yes Yes Yes Yes Yes Yes Yes Yes N3004 3093 3027 2523 2468 2489 2489 1127 No. of groups 100 105 103 86 84 85 85 42 log-likelihood 7496.271 7744.186 7767.310 6751.915 6597.227 6666.484 6688.275 3039.778 Within R-squared 0.270 0.264 0.338 0.449 0.455 0.425 0.435 0.579 Static model using within-group estimator All models use annual data from 1960 to 2016 Clustered standard errors at country level in parentheses ∗(p<0.1), ∗∗(p<0.05), ∗∗∗(p<0.01) 123