I am Interim Professor ("Vertretungsprofessor") of Evidence-based Political Research at the University of Mannheim, where I also head the Emmy-Noether research group Making Diversity Work at the Mannheim Center for European Social Research (MZES). My work spans both Sociology and Political Science, with a focus on the study of group relations, language and identity, social norms, and civic behavior. Major applications include research on immigration, ethnic diversity, and state- and nation-building.
My work has been published or is forthcoming in the American Political Science Review, the American Journal of Political Science, the Journal of Politics, the Proceedings of the National Academy of Sciences (PNAS), the American Journal of Sociology, the European Sociological Review, and Sociological Science, amongst other outlets.
I hold a Ph.D. in Political Science from Stanford University, a J.D. from Stanford Law School, and a double B.A. in Economics and Political Science from the University of California, Berkeley. I have held prior positions at the Max Planck Institute for Research on Collective Goods and the European University Institute.
Melissa Lee, Nan Zhang and Tilmann Herchenröder. 2023. From Pluribus to Unum? The Civil War and Imagined Sovereignty in 19th Century America.
American Political Science Review. Online First.
Contestation over the structure and location of final sovereign authority -- the right to make and enforce binding rules -- occupies a central role in political development. Historically, war often settled these debates and institutionalized the victor's vision of sovereignty. Yet sovereign authority requires more than institutions; it ultimately rests on the recognition of the governed. How does war shape imagined sovereignty? We explore the effect of warfare in the United States, where the debate over two competing visions of sovereignty erupted into the American Civil War. We exploit the grammatical shift in the ``United States'' from a plural to a singular noun as a measure of imagined sovereignty, drawing upon two large textual corpuses: newspapers (1800--1899) and Congressional speeches (1851--1899). We demonstrate that war shapes imagined sovereignty, but for the North only. Our results further suggest that Northern Republicans played an important role as ideational entrepreneurs in bringing about this shift.
Mathias Poertner and Nan Zhang. 2023. The Effects of Combating Corruption on Institutional Trust and Political Engagement: Evidence from Latin America.
Political Science Research and Methods. Online First.
While a number of high-level figures around the world have been prosecuted and even jailed for corruption in recent years, we know little about how such anticorruption efforts shape public opinion and patterns of political engagement. To address this question, we examine evidence from Argentina and Costa Rica involving the unprecedented sentencing of two former Presidents on corruption charges. Exploiting the coincidence in timing between these cases and fieldwork on nationally representative surveys, we find that citizens interviewed in the aftermath of these events expressed lower trust in institutions and were less willing to vote or join in collective demonstrations. Overall, these findings suggest that high-profile efforts to punish corrupt actors may have similar effects as political scandals in shaping citizens' relationship to the political system.
Nate Breznau, Eike Mark Rinke, Alexander Wuttke, Hung H.V. Nguyen...Nan Zhang and (160 others). 2022. Observing Many Researchers Using the Same Data and Hypothesis Reveals a Hidden Universe of Uncertainty.
Proceedings of the National Academy of Sciences. 119(44):e2203150119.
This study explores how researchers' analytical choices affect the reliability of scientific findings. Most discussions of reliability problems in science focus on systematic biases. We broaden the lens to emphasize the idiosyncrasy of conscious and unconscious decisions that researchers make during data analysis. We coordinated 161 researchers in 73 research teams and observed their research decisions as they used the same data to independently test the same prominent social science hypothesis: that greater immigration reduces support for social policies among the public. In this typical case of social science research, research teams reported both widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers# expertise, prior beliefs, and expectations barely predict the wide variation in research outcomes. More than 95% of the total variance in numerical results remains unexplained even after qualitative coding of all identifiable decisions in each team's workflow. This reveals a universe of uncertainty that remains hidden when considering a single study in isolation. The idiosyncratic nature of how researchers' results and conclusions varied is a previously underappreciated explanation for why many scientific hypotheses remain contested. These results call for greater epistemic humility and clarity in reporting scientific findings.
David Kretschmer, Johanna Gereke, Fabian Winter, and Nan Zhang. No Differential Effects of Classroom Ethnic Composition on Native and Immigrant Friendship Segregation: A Comment on Smith et al. 2016. American Journal of Sociology. Accepted.
What is the relationship between classroom ethnic composition and patterns of ethnic friendship segregation amongst native and immigrant adolescents? In a 2016 AJS article, Smith et al. analyzed data on adolescents' friendship networks from four European countries and found differential effects of classroom composition on natives' and immigrants' friendship choices. In this comment, we identify estimation problems in a large number of classroom networks included in Smith et al.'s original study. We demonstrate that immigrant homophily cannot be meaningfully estimated in many networks containing insufficient numbers of immigrant students from the same ethnic group. After accounting for these estimation problems at the network level, our re-analyis provides little evidence that classroom composition has differential effects for native and immigrant homophily.
Johanna Gereke, Joshua Hellyer, Jan Behnert, Saskia Exner, Alexander Herbel, Felix Jäger, Dean Lajic, Štěpán Mezenský, Vu Ngoc Anh, Tymoteusz Ogłaza, Jule Schabinger, Anna Sokolova, Daria Szafran, Noah Tirolf, Susanne Veit, and Nan Zhang. 2022. Demographic change and group boundaries in Germany: The effect of projected demographic decline on perceptions of who has a migration background. Sociological Science. 9(9):206-220.
In many Western societies, the current "native" majority will become a numerical minority sometime within the next century. How does the prospect of demographic change affect existing group boundaries? An influential recent article by Abascal (2020) showed that White Americans under demographic threat reacted with boundary contraction -- that is, they were less likely to classify ambiguously White people as "White." The present study examines the generalizability of these findings beyond the American context. Specifically, we test whether informing Germans about the projected decline of the "native" population without migration background affects the classification of phenotypically ambiguous individuals. Our results show that information about demographic change neither affects the definition of group boundaries nor generates negative feelings towards minority outgroups. These findings point to the relevance of contextual differences in shaping the conditions under which demographic change triggers group threat and boundary shifts.
Nan Zhang, Johanna Gereke and Delia Baldassarri. 2022. Everyday Discrimination in Public Spaces: A Field Experiment in the Milan Metro. European Sociological Review. 38(5):679-693.
A large scholarship documents discrimination against immigrants and ethnic minorities in institutional settings such as labour and housing markets in Europe. We know less, however, about discrimination in informal and unstructured everyday encounters. To address this gap, we report results from a large-scale field experiment examining the physical avoidance of immigrants as an unobtrusive yet important measure of everyday discrimination in a multiethnic European metropolis. In addition to varying confederates’ migration background and race, we also vary signals of status (business versus casual attire) in order to shed light on the mechanisms underlying discriminatory patterns. We find that natives are averse to contact with Nigerian confederates, but do not discriminate against Chinese confederates. Furthermore, manipulating confederates’ attire has little effect on natives’ behaviour. Overall, our results highlight the everyday burdens borne particularly by individuals of African descent in commonplace, ‘street-level’ encounters.
Nan Zhang and Melissa Lee. 2020. Literacy and State-Society Interactions in 19th Century France. American Journal of Political Science. 64(4): 1001-1016.
- Winner of the 2020 Best Article Prize, European Politics and Society Section, American Political Science Association
Modern states are distinguished by the breadth and depth of public regulation over private affairs. This aspect of state capacity and state power is predicated on frequent and dense encounters between the state and the population it seeks to control. We argue that literacy in the language of state administration facilitates state–society interaction by lowering the transaction costs of those encounters. We support this claim with evidence drawing upon detailed historical data from nineteenth‐century France during a crucial period of state and nation building. Focusing on the specific domain of French marriage regulations, we find that increasing literacy predicts greater popular involvement with local authorities across French regions over time. These results demonstrate that literacy plays an important role in political development not solely by enhancing loyalty to the state, as the literature has recognized, but also by lowering linguistic and human capital barriers to state–society interaction.
Nan Zhang, Amelie Aidenberger, Heiko Rauhut and Fabian Winter. 2019. Prosocial Behavior in Interethnic Encounters: Evidence from a Field Experiment with High- and Low-Status Immigrants. European Sociological Review 35(4): 582–597.
- Winner of the European Sociological Review Best Article of the Year Prize 2020
Recent waves of immigration have changed the demographic face of European societies and fueled considerable debate over the consequences of ethnic diversity for social cohesion. One prominent argument in this debate holds that individuals are less willing to extend trust and solidarity across ethnic lines, leading to lower social capital in multiethnic communities. We present a direct test of this proposition in a field experiment involving native-immigrant interactions in Zurich's Central Train Station. Our intervention consists of approaching commuters with a small request for assistance (borrowing a mobile phone), which we take as a measure of prosociality. We further differentiate between reactions towards natives as well as both high- and low-status immigrant groups. Compared to native-native interactions, we find lower solidarity in native-immigrant encounters, especially in cases involving stereotypically low-status immigrants. In exploratory analyses, we further show that discrimination only obtains in 'low cost' situations where commuters could easily justify not helping (e.g. by claiming not to carry a phone). Overall our results shed light on key theoretical mechanisms underlying patterns of solidarity in contemporary multiethnic societies.
Fabian Winter and Nan Zhang. 2018. Social Norm Enforcement in Ethnically Diverse Communities. Proceedings of the National Academy of Sciences 115(11): 2722-2727.
How does ethnic diversity influence the maintenance of social norms in complex, Western societies? We provide evidence from a natural field experiment examining reactions to norm violations in multiethnic German neighborhoods. We uncover asymmetric patterns of norm enforcement in interethnic encounters: “Native” Germans are more active in sanctioning norm violations, while ethnic minorities are more likely to be targeted for sanctions. We link these dynamics to prevailing status inequalities between minorities and natives in German society. We further show that, as a consequence of such asymmetries, social control tends to rise with ethnic diversity.
Nan Zhang. 2018. Institutions, Norms, and Accountability: A Corruption Experiment with Northern and Southern Italians. Journal of Experimental Political Science 5(1): 11-25.
Anti-corruption research has highlighted the potential for grassroots monitoring to improve governance outcomes, but the conditions under which citizens are willing to report bribery remain under-studied. Are individuals from some societies socialized into a “culture of corruption” that makes them more accepting of malfeasance, or is the failure to denounce wrongdoing simply a response to low-quality enforcement institutions? I conduct a laboratory experiment to examine how the propensity to report corruption differs between Northern and Southern Italians, two populations experiencing different levels of corruption in everyday life. For each group, I experimentally manipulate the quality of enforcement institutions. When given high-quality institutions, all participants are more willing to report corruption. Moreover, Southerners and Northerners behave similarly when placed within the same institutional environments. These results suggest that high-corruption societies are not “culturally” predisposed to tolerate malfeasance. Rather, improving the capacity of enforcement institutions may significantly strengthen accountability norms.
Melissa Lee and Nan Zhang. 2017. Legibility and the Informational Foundations of State Capacity. Journal of Politics 79(1): 118–132.
Recent research in political science has stressed the importance of the state in curbing violence and promoting social and economic development, resulting in an explosion of scholarly interest in the foundations of state capacity. This article argues that state capacity depends in part on “legibility”—the breadth and depth of the state’s knowledge about its citizens and their activities—and that legibility is crucial to effective, centralized governance. We illustrate the importance of legibility through a novel argument linking legibility to the state’s role in curbing free-riding in collective action dilemmas. We then demonstrate this argument in the context of tax contributions to public goods using an original measure of legibility based on national population censuses. The article concludes by discussing how future research may leverage our indicator’s exceptional temporal and geographic coverage to advance new avenues of inquiry in the study of the state.
Nan Zhang, Giulia Andrighetto, Stefania Ottone, Ferruccio Ponzano, and Sven Steinmo. 2016. Willing to Pay? An Experimental Analysis of Tax Compliance in Britain and Italy. PLoS ONE 11(2): e0150277.
As shown by the recent crisis, tax evasion poses a significant problem for countries such as Greece, Spain and Italy. While these societies certainly possess weaker fiscal institutions as compared to other EU members, might broader cultural differences between northern and southern Europe also help to explain citizens’ (un)willingness to pay their taxes? To address this question, we conduct laboratory experiments in the UK and Italy, two countries which straddle this North-South divide. Our design allows us to examine citizens’ willingness to contribute to public goods via taxes while holding institutions constant. We report a surprising result: when faced with identical tax institutions, redistribution rules and audit probabilities, Italian participants are significantly more likely to comply than Britons. Overall, our findings cast doubt upon “culturalist” arguments that would attribute cross-country differences in tax compliance to the lack of morality amongst southern European taxpayers.
Giulia Andrighetto, Nan Zhang, John D'Attoma, Stefania Ottone, Ferruccio Ponzano, and Sven Steinmo. 2016. Are Some Countries More Honest than Others? Evidence from a Tax Compliance Experiment in Sweden and Italy. Frontiers in Psychology 7: 472.
This study examines cultural differences in ordinary dishonesty between Italy and Sweden, two countries with different reputations for trustworthiness and probity. Exploiting a set of cross-cultural tax compliance experiments, we find that the average level of tax evasion (as a measure of ordinary dishonesty) does not differ significantly between Swedes and Italians. However, we also uncover differences in national “styles” of dishonesty. Specifically, while Swedes are more likely to be either completely honest or completely dishonest in their fiscal declarations, Italians are more prone to fudging (i.e., cheating by a small amount). We discuss the implications of these findings for the evolution and enforcement of honesty norms.
Nan Zhang. 2015. Changing a ‘Culture’ of Corruption: Evidence from an Economic Experiment in Italy. Rationality & Society 27(4): 387-413.
Empirical evidence demonstrates that bribery, extortion and graft are often the outgrowths of a deeper ‘culture of corruption’ which has proved disconcertingly resilient in the face of public sector reforms. This article investigates whether changing collective beliefs about how ‘most people in society’ will behave can reform prevailing cultural practices. Employing an economic experiment involving northern and southern Italian university students, this study shows that (costly) honest behavior can be sustained by conditional beliefs about the honesty of others. I also hypothesize that, given southern Italians’ reputation for corruption, informing participants that they are interacting with southerners should increase the level of bribery in the experiment. However, surprisingly, I find the opposite effect: when exposed to information about the identity of their fellow participants, southern Italians are not only less corrupt, but they are also more likely to believe that their counterparts are less corrupt. I discuss several explanations which may account for these unexpected findings. Overall, the paper provides theoretical foundations and experimental support for how new cultural practices might emerge.
David Laitin and Nan Zhang. 2012. Political Culture. in the Oxford Companion to Comparative Politics. Joel Krieger (ed). New York: Oxford University Press.
Making Diversity Work
Recent trends in global migration have raised public concerns about the potentially negative consequences of ethnic diversity for social solidarity in Western societies. Few studies to date however have sought to explain how trust and cooperation can conversely be sustained in diverse settings. Against this backdrop, the Making Diversity Work project aims to create novel behavioral indicators of social cohesion across multiethnic German neighborhoods in order to analyze the emergence of positive community relations. In contrast to existing studies which predominately privilege comparisons between ethnically-homogenous and heterogeneous areas, a key contribution of this project is to focus explicitly on important unexamined differences between highly-diverse contexts in order to understand the conditions under which diversity may undermine or, conversely, promote cooperation.
Using innovative field experimental methods, this project will develop a sophisticated set of behavioral indicators to map variation in “prosocial” behavior across diverse urban areas. Further, this new data will be used to (i) systematically test novel theories about how different features of diverse neighborhoods contribute to local cooperation, (ii) disentangle the behavioral mechanisms – other-regarding preferences, social norms enforcement, and intergroup contact – underlying social cohesion in multiethnic settings, and (iii) develop a richer understanding of social relations that takes both natives’ and minorities’ experiences into account. Overall, results from this research will open up new scientific perspectives on cooperation in diverse communities and generate critical policy knowledge about how to “make diversity work" in an era of rapid demographic change.
This project is funded by the Emmy-Noether program of the German Research Foundation (DFG).
Research in Progress (Selected)
Military Service and Immigrants’ Assimilation: Evidence from the Vietnam Draft Lotteries.
with Melissa Lee.
Recent trends in global migration have raised questions surrounding immigrants’ national identification and assimilation into the American mainstream. What explains variation in immigrants’ integration choices? Although seminal theories in political science argue that military service is a critical driver of integration, scholars have challenged the empirical basis and theoretical logic underpinning this relationship. A major obstacle bedeviling the study of military service and integration is self-selection: immigrants who are better assimilated may be more likely to join the military in the first place. We address the selection problem by examining the effects of military conscription during the Vietnam War using an instrumental variables approach. Conscription during the crucial years 1970–1972 was decided on the basis of national draft lotteries which assigned draft numbers based on an individual’s date of birth. We use the draft lottery to instrument for military service and estimate the causal effect of service on a range of integration outcomes using granular data from the 2000 decennial census. Our study thus contributes novel evidence to key debates on the implications of military service for assimilation and national identification, while also highlighting a potential role for public policy to encourage immigrant incorporation via national service.
Cross-cutting Cleavages and Native-Refugee Contact: Evidence from Germany.
with Alexandra Kommol.
The arrival of large numbers of asylum seekers in many European countries has raised critical questions concerning refugee integration. While prior research has examined individual characteristics (e.g. refugees’ educational attainment) and contextual conditions (e.g. local unemployment rates) as additive factors underlying social integration, we argue that complementarities between individual refugees and their place of resettlement can further enhance refugee-native contacts. Using data from the IAB-BAMF-SOEP Survey of Refugees and leveraging the exogenous assignment of asylum seekers in Germany, we show that similarity in marital status between individual refugees and their host communities increases social integration, but for women only. These findings carry important implications given that female refugees report considerably fewer interactions with natives in the first place. Consequently, female refugees may stand to benefit from allocation policies that take “contextual fit” into account when assigning asylum seekers to places of residence.
Cultural Adaptation and Demographic Change: Evidence from Mexican-American Naming Patterns During the California Gold Rush.
with Maria Abascal.
According to new assimilation theory, assimilation can entail not only the adoption, by immigrants, of the established population's cultural practices, but also the adoption, by the established population, of immigrants' cultural practices. However, empirical research on assimilation has either neglected adaptation on the part of the established population or identified only modest changes. We examine reactions to a massive and rapid inflow of immigrants, and specifically, those of Mexican-origin Californios around the time of the Gold Rush of 1849. Treating naming patterns as indicators of assimilation, we find that Mexican American children born in California after 1849–––and especially boys–––were significantly less likely to receive distinctively Hispanic first names. As a placebo test, we further show that a similar pattern does not obtain in areas (e.g. New Mexico) that did not experience a rapid inflow of new American settlers. The findings validate an important insight of new assimilation theory, as well as shed new light on contemporary research on demographic change.
Politics of Ethnic Diversity. BA Seminar, University of Mannheim. Fall 2023.
Introduction to Causal Inference. BA Seminar, University of Mannheim. Fall 2023.
Research Design. MA / PhD Lecture, University of Mannheim. Fall 2023.
Field Experiments. MA / PhD Seminar, University of Mannheim. Spring 2023.
Ethnic Diversity and Social Cohesion. BA Seminar, University of Mannheim. Fall 2022.