Counterfactual Slopes and Their Applications in Social Stratification

This article addresses two prominent theses in social stratification research, the great equalizer thesis and Mare’s school transition thesis. Both theses describe the role of an intermediate educational transition in the association between socioeconomic status and an outcome variable. However, the descriptive regularities of the two theses may be driven by differential selection into the intermediate transition, which prevents the two theses from having substantive interpretations. The authors propose a set of novel counterfactual slope estimands, which capture these theses under hypothetical interventions that would eliminate the differential selection. The authors thereby construct selection-free tests for these theses. The authors are the first to explicitly provide nonparametric causal estimands for the great equalizer thesis and the school transition thesis, which enable them to conduct more principled analysis. The authors are also the first to develop flexible, efficient, and robust estimators for the two theses on the basis of efficient influence functions. The authors apply this framework to a nationally representative data set in the United States and reevaluate the two theses. Findings from the selection-free tests suggest that the descriptive regularities are misleading for the substantive interpretation of the great equalizer thesis, but not for the school transition thesis. Additionally, the counterfactual slopes provide a new framework for evaluating the inequality impacts of policy interventions.