In this article, I present the second version of the Citizenship Regime Inclusiveness Index (CITRIX 2.0). It measures the inclusiveness of regulations for immigrants’ access to citizenship across 23 OECD countries from 1980 to 2019, zooming in on four essential policy components: conditions regarding (1) birthright; (2) residence; (3) renunciation; and (4) integration. While explaining the construction of the dataset, I advance a synthetic approach to index methodology. The main idea of this approach is to use statistical dimensionality tests to validate deductively specified additive concept structures. This is the first lesson we can learn from CITRIX. After validating the index in terms of content, dimensionality, and convergence, a short empirical analysis presents two additional lessons. First, after two cycles of liberalization and subsequent restrictive turns, mostly in integration conditions, aggregate citizenship policy inclusiveness has stagnated, but liberalized overall. 2003 marks the peak of liberalization. Second, there has been long-term convergence constituted by two phases of convergence with one diverging phase in between. I conclude that liberalization is more limited, and convergence more pronounced, than often assumed. CITRIX offers a versatile toolbox for future research to explore citizenship policies and their correlates. Regular updates are planned.
- CITRIX shows that liberalization in citizenship for immigrants has stagnated, and that policies have converged over the long run. Policymakers should consider these findings to situate and inform future citizenship reforms.
- Policymakers should be aided by social scientists and policy analysts in their search for better policies by employing CITRIX to explain variation in citizenship policies and to study their effects on immigrant integration and other social outcomes.
- CITRIX develops synthetic approach to index construction. Social scientists and policy analysts should consider this approach when designing tools to measure and compare policies.
- Funding institutions should consider investing in efforts to update and expand datasets that measure critical public policies. The second version of CITRIX highlights this potential.
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