Principal investigator: Omar Barroso Khodr
Authors: Manuel Bagues and Pamela Campa
Original title: Can gender quotas in candidate lists empower women? Evidence from a regression discontinuity design
Location of the Intervention: Spain
Sample Size: Municipalities with more than 3.000 inhabitants
Primary Variable of Interest: The impact of introducing quotas in 2007, leveraging the variation provided by municipalities that in January 2006 had approximately 5.000 inhabitants; to study the extent of the quotas in 2011.
Type of Intervention: Quota policies and incentives for elections.
Methodology: Multiple linear regression; Regression discontinuity (RDD); Comparative study; and Optimization study.
Summary
The authors present a comprehensive analysis of the short- and medium-term effects of gender quotas on candidate lists, using evidence from local elections in Spain. Within a closed-list system with proportional representation, quotas were introduced in 2007 in municipalities with more than 5.000 inhabitants and extended in 2011 to municipalities with more than 3.000 inhabitants. Using the Regression Discontinuity Model, the authors found that quotas increased the participation of women on candidate lists by approximately 8 percentage points and among council members by 4 percentage points. However, across three election rounds, no significant variation was observed in several variables related to the quality of politicians, the likelihood of women reaching powerful positions such as party leader or mayor, or the size and composition of public finances. Overall, the analysis suggests that quotas on candidate lists fail to remove the barriers preventing women from playing an influential role in politics.
- Policy Problem
According to the authors, several relevant political issues are identified regarding the implementation and effectiveness of gender quotas for candidates. These issues highlight that quotas are not a simple and universal solution, and that their success depends on careful planning and contextual factors.
One of the central policy issues concerns the design and application of the quota laws themselves. The study emphasizes that, for quotas to effectively increase the number of women on candidate lists, they must be mandatory and properly enforced (Besley et al., 2017). A critical planning flaw that policymakers must address is the possibility of parties manipulating the system—for example, by allocating women to ineligible positions on party lists, which would compromise the intended impact of the measure (Born et al., 2019).
Furthermore, the study addresses the controversial issue of candidate quality, bringing to light a debate that deserves the attention of policymakers. On the one hand, quotas can encourage parties to select more qualified female candidates. On the other hand, if there is a perception of a shortage of women with the appropriate profile, quotas may, at least in the short term, generate concerns about a reduction in the average quality or experience of candidates—an argument that can be politically exploited against their implementation.
The study also highlights voter behavior and social biases as significant political challenges. The success of quotas can be compromised if a significant portion of the electorate demonstrates resistance to female leadership, as indicated by data from the World Values Survey. This suggests that simply introducing quotas is insufficient; it may be necessary to complement them with public information campaigns or civic education initiatives aimed at transforming electoral attitudes and preventing lists with greater female representation from being penalized at the polls. This issue is especially critical in open-list electoral systems, where voters have direct influence over the elected candidates, and pre-existing biases can severely limit the effectiveness of quotas.
Another dimension of political issues concerns long-term objectives, which go beyond numerical representation. The study discusses the so-called “trickle-up"According to which quotas can facilitate women's access to leadership positions, this progress can be hampered by persistent networks of male influence within parties. Thus, public policies must go beyond quotas for candidacies, including measures that reform the internal structures of parties and promote the advancement of women in political organizations."
Finally, the relationship between descriptive representation (presence of women in public office) and substantive representation (policies that address women's interests) is presented as conditional. The study points out that political change is more likely when women reach leadership positions or achieve a "critical mass," indicating that quotas aimed at only a minimum number of representatives may be insufficient to generate significant transformations. Policymakers should therefore consider whether quota rules should also include leadership positions in legislatures and parties, in order to ensure that female presence translates into effective influence.
- Policy Implementation Context
The context of this research is centered on the implementation of a legislated gender quota policy for municipal elections in Spain, established by the Equality Law of 2007. The most relevant aspect of its design is the selective application based on a population criterion, strategically explored by the researchers. According to the authors, initially, in 2007, the law was applied only to municipalities with more than 5.000 inhabitants, and was later extended, in 2011 and 2015, to those with more than 3.000. This criterion is not arbitrary; it aligns with the Spanish administrative structure, in which these limits already determine legal obligations, council composition, and municipal financial resources, configuring an ideal cutoff point for a Regression Discontinuity analysis.
According to the authors, the policy was implemented within the proportional representation electoral system using closed lists—an essential detail for understanding its impact. In this model, voters vote for pre-ordered party lists, and party leaders have total control over the candidates' positions. The order on the list is crucial for the election, especially for the mayoral position. The quota directly interfered with this process, requiring that each list and each group of five candidates include at least 40% representatives of each gender, under penalty of ineligibility.
Finally, the authors highlight the importance of the broad multi-party political support and popular acceptance that the law received, factors that facilitated its implementation. However, the exemption granted to smaller municipalities—initially with fewer than 5.000 inhabitants and, subsequently, fewer than 3.000—is significant, supposedly motivated by concerns about the situation of women in rural areas. This gradual, population-based implementation created a quasi-experimental scenario, allowing researchers to compare very similar municipalities—some subject to the quota and others not—and thus isolate the causal effect of the policy from other factors over three electoral cycles (2007, 2011, and 2015).
- Evaluation Details
The study focuses on approximately 5.000 small Spanish municipalities, with populations between 250 and 10.000 inhabitants, which together represent about 20% of the national population. The research highlights that these municipalities present distinct demographic characteristics compared to larger cities, being marked by an older population, lower levels of education, and a smaller proportion of women.
In these areas, gender stereotypes are more pronounced: there is a significantly higher percentage of residents who agree with the idea that men should be given priority for jobs when these are scarce, as well as a lower level of concern about gender discrimination, compared to urban centers.
The analysis is based on a comprehensive database covering four election cycles (2003, 2007, 2011, and 2015), including information on candidate lists, election results, council member profiles, municipal budgets, political preferences, and economic indicators. Regarding candidates, the data reveals that, before the introduction of gender quotas in 2007, only 29% were women—and their presence in the top positions on electoral lists was even lower, reaching only 17%.
In this context, the study also highlights significant gender disparities in relation to political experience: male candidates were 10 percentage points more likely to have prior experience and to run again in future elections. Furthermore, the researchers used surname analysis to identify possible family ties, finding that approximately 5,5% of the candidates shared the same surname as the party leader—suggesting a significant level of nepotism in the candidate selection process.
- Method
The authors use a regression discontinuity design (RDD) to assess the impact of a gender quota policy on municipal elections. The implementation of the policy was determined by a strict population criterion: municipalities with a population above a certain limit were required to adopt the quota, while those below that level were exempt. To analyze the initial quota in 2007, the researchers compared municipalities that, in January 2006, had slightly more than 5.000 inhabitants with those that had slightly fewer. Similarly, to examine the extent of the policy in 2011, the comparison was made between municipalities close to the 3.000-inhabitant limit, based on data from January 2010.
According to the authors, the analysis was conducted using specific regression equations, developed for each quota implementation event. The central principle of the method consists of comparing the results (Y) between municipalities located immediately above and below the population limits, based on the assumption that these units are comparable to each other. The research was not limited to the immediate effect of the policy (when k = 0), but also investigated its long-term impacts. To this end, the same groups of municipalities were followed throughout the subsequent electoral cycles, in 2011 and 2015, with the aim of observing how multiple exposures to the quota policy influenced the results.
From a methodological standpoint, the study employed a local linear estimate within an optimal range, using a triangular kernel to assign weights to observations according to their proximity to the population limit. The researchers applied robust inference techniques and used pooled standard errors at the municipal level when necessary. To improve the accuracy of the estimates, controls were also included for lagged values of the outcome variable, as well as for the proportion of female candidates and councilwomen before the implementation of quotas.
- Main results
According to the authors, the quotas successfully achieved their immediate objective, increasing the proportion of female candidates by 8 percentage points and that of female councilors by 4 percentage points. However, the broader objectives of the study—such as promoting women's access to leadership positions or influencing public policies to better reflect the preferences of the female public—were not achieved, at least in the three electoral cycles analyzed.
Meanwhile, the authors highlight that the analysis found no evidence to support the recurring criticism that quotas compromise the quality of elected politicians. Indicators such as educational level and electoral performance of the most impacted party lists did not reveal a significant drop in quality.
In this context, the authors make some important reservations. The study focused on smaller municipalities, characterized by low female participation in the labor market and more conservative gender attitudes. Thus, the results may reflect the effects of applying quotas in similar environments, without necessarily extending to other contexts. Furthermore, the interval of three electoral cycles may have been insufficient to capture long-term impacts, and the relatively modest increase of 4 percentage points in the number of female councilors may have been too small to bring about more profound transformations.
The study is also largely limited to analyzing a single mechanism—changes in local candidate lists—without considering other potential channels, such as the symbolic value of quotas, the role of national role models, or the subsequent political advancement of elected women. Because the impact of quotas is heavily conditioned by context, the authors conclude that further research in different settings is needed to achieve a more comprehensive understanding of electoral dynamics.
- Lessons in Public Policy
This study investigates the impact of gender quota laws on municipal elections across four main dimensions: the composition of candidate lists, voter behavior, the composition of the local council, and public policies. The analysis employs a rigorous methodological approach, using regression discontinuity (RD) models around population thresholds of 3.000 and 5.000 inhabitants to identify causal effects, and reports robust results across different bandwidths and model specifications.
The most significant findings relate to the composition of candidate lists. The research conclusively demonstrates that quotas were highly effective in their primary objective: they successfully increased the overall proportion of female candidates by approximately 8 to 9 percentage points in the first election after implementation. However, this increase was strategically implemented. Parties complied with the law primarily by placing women in the lowest positions within the mandatory five-position range, resulting in only a very modest increase (2 percentage points) in female representation in the highest and most electable positions on the ballots. Critically, this initial momentum did not intensify in subsequent elections, indicating that quotas created a “ceiling” rather than a “floor” for female representation.
Other important findings include the fact that quotas did not have several potential negative consequences often feared by critics. There was no evidence that the policy led parties to withdraw from elections, nor did it lead to an increase in nepotism (measured by candidates sharing the surname of the party leader). The study also found a short-term, mechanical decrease in the political experience of candidates as new women were brought in to fulfill the quota, but this effect diminished over time as these new candidates gained experience. Finally, quotas did not have a statistically significant impact on the proportion of women party leaders, either immediately or in the two subsequent election cycles observed.
References
Besley, T.J., Folke, O., Persson, T. & Rickne, J., 2017. Gender quotas and the crisis of the mediocre man: theory and evidence from Sweden. American Economic Review, 107(8), pp.2204–2242.
Born, A., Ranehill, E. & Sandberg, A., 2019. A Man's World? The Impact of a Male Dominated Environment on Female Leadership. University of Gothenburg Working Paper.
