Josep Serrano-Serrat

Josep Serrano-Serrat

Postdoctoral Researcher at the Institute for Public Goods and Policies (IPP), Spanish National Research Council (CSIC).

Research

Publications

  1. Quantities of Interest for Interactions and the Pitfalls of Assuming Linear Treatment Effects
    Sociological Science (2026), 13, 945–970.
    [Abstract]
    While quantitative social sciences often rely on estimating models in which treatment effects vary across groups, researchers rarely specify which causal quantity they aim to estimate or justify their empirical modeling choices. This paper makes two contributions. First, it clarifies the distinct quantities of interest when studying interactions: comparisons at different treatment intensities (the difference in Conditional Average Marginal Effects) and comparisons at similar intensities (what I term the Average Interactive Partial Effect). When treatment effects are non-linear and treatment distributions differ across groups, these quantities diverge. Second, the paper assesses estimation strategies to estimate these quantities. It demonstrates that linear interaction models produce biased estimates of either quantity when treatment effects are non-linear and explores two alternatives that explicitly accommodate such non-linearities. This paper is accompanied by an "R" package that implements these approaches. Through simulations, stylized examples, and an empirical application, the paper shows that explicitly defining the quantity of interest and selecting appropriate models is essential for valid interaction analysis.
  2. Occupational Labor Markets, Skills, and Immigration Concerns: Panel Data Evidence for Germany
    European Journal of Political Research (First View)
    [Abstract]
    Economic crises, technological change, and labor market transformations have long shaped political attitudes, particularly toward immigration. While existing research links occupational risks to anti-immigration preferences, which specific occupations drive this relationship remains underexplored. This research note addresses this gap by examining how occupation-specific skills (OSS) – defined as the amount of skills required to work in a given occupation – moderate the relationship between occupational labor market conditions and immigration attitudes. Drawing on sociological and comparative political economy perspectives, the paper argues that individuals with high levels of OSS are especially sensitive to deterioration in their occupation’s labor market conditions. The central theoretical implication is that adverse changes in occupational labor markets generate stronger political anti-immigration reactions among high-OSS workers, including Managers and (Associate) Professionals. Importantly, OSS are conceptually distinct from other occupational dimensions used in the literature, such as task specificity, and from other skill dimensions, such as general skill. The empirical analysis draws on over 20 years of longitudinal data from the German Socio-Economic Panel (GSOEP), finding evidence consistent with the argument. The findings contribute to ongoing debates about the political behavior of high-skilled workers, a group whose attitudes toward immigration remain contested.
  3. South-South Immigration and Redistribution Preferences: Evidence from Colombia
    (with Ignacio Jurado) · World Politics (2026), 78(3), 602-641.
    [PDF] [Abstract]
    Research on the effects of immigration on redistribution preferences mostly focus on Western countries and neglect the South-South contexts. However, we argue that immigration shocks may have different effects in South-South regions. On the one hand, the effect should be more muted due to the minimal cultural differences and the limited development of the welfare state. On the other hand, the impact might be even larger due to high inequality and scarce resources. To investigate this, we follow a two-fold strategy. First, we exploit the 2015 Venezuelan immigration shock in Colombia using a difference-in-differences strategy complemented with an instrumental variable, finding null-to-positive effects. Secondly, a survey experiment reveals that priming citizens on immigration has positive effects on social spending preferences. We attribute this to deservingness considerations. These results challenge some prevailing theories and suggest that increased immigration does not necessarily reduce redistribution preferences in South-South contexts.
  4. Occupation-Specific Skills, Labor Market Context, and Preferences for Redistribution
    the Journal of Politics (2026), 88(3), 1145–1161.
    [PDF] [Abstract]
    Understanding who supports income redistribution and when is at the core of political economy literature. Nevertheless, even though social stratification literature understands skill specificity as a key element of social class, there are contradictory views on the role it plays in shaping political preferences. I elaborate a framework that provides an understanding of these contradictions. I argue that the effects of occupation-specific skills on redistribution preferences are moderated by the occupational context, being more negative the tighter the occupational labor market is. I propose two mechanisms related to labor market prospects to explain this relationship: occupational expected wages and risk exposure. Using data from the European Social Survey, the International Social Survey Programme, and flexible interactive effects models, I show the relevance of this new approach. This analysis contributes to a more nuanced understanding of the heterogeneity of middle-class political attitudes.
  5. Shouldering Childhood: Early Behavioral Traits and Discrimination Concerns
    (with Maria Rubio-Cabañez) · European Sociological Review (2026), 42(1), 131–145.
    [Abstract]
    This study examines how childhood emotions, traits, and behaviours influence concerns about gender inequality and racism in young adulthood. Drawing on the social psychology and social science literature, it examines whether childhood behavioural traits measured by the Strengths and Difficulties Questionnaire (SDQ) influence concerns about discrimination. Using the Growing Up in Ireland longitudinal dataset, the study shows that, among native males, internalizing behaviours in childhood (such as loneliness and frequent worry) correlate positively with later concerns about discrimination, while externalizing behaviours (such as strong temperament and impulsivity) show a negative correlation. Finally, native males with stronger prosocial traits are more concerned about racism. However, for females and foreigners—social groups that are typically discriminated against—these associations are not statistically significant. The results suggest that childhood behavioural traits shape political attitudes before political preferences crystallize and underscore the importance of understanding the developmental origins of discrimination concerns.

Working Papers