Graduation rates are critical performance metrics for higher education institutions, reflecting student success and the effectiveness of educational programs. Among various factors, the complexity of university curricula, measured by prerequisite course sequences, total credit requirements, and course flexibility within degree programs, significantly influences outcomes such as timely graduation and retention rates. Previous studies analyzing these effects often lack a unified framework to address how factors such as gender, academic preparation, and socioeconomic background shape these relationships. Using data from 26 U.S. universities funded by the Ascendium Foundation, this study employs a multifaceted causal inference framework to evaluate the impact of curricular complexity on graduation rates. Our methodology combines Hierarchical Linear Models (HLM) to account for the nested structure of students within universities, Generalized Propensity Scores (GPS) to adjust for confounders, and Double Machine Learning (DML) within GPS-stratified quintiles to provide robust causal estimates. Furthermore, we construct and refine a causal network using the Peter-Clark (PC) Algorithm and the Bayesian Information Criterion (BIC) score, with sensitivity analysis to
ensure robustness. Our results reveal a significant negative causal relationship between curricular complexity and four-year graduation rates, with an effect of -3.88% per unit increase in complexity. Sensitivity analysis supports the robustness of this relationship, showing a consistent effect of -3.76% when accounting for unobserved confounders. Introducing a hidden node representing socioeconomic status in our causal network further strengthens these findings, showing minimal change in the estimated effect even when accounting for potential unobserved factors. These findings suggest that complex curricula create barriers to completing the degree in time, underscoring the need for educational strategies that balance academic rigor with accessibility. This study provides a foundation for evidence-based policy reforms that aim to improve student success through optimized curricular design.
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