The economic returns to citizenship: Evidence from a meta-analysis.

Citizenship is widely summarized as producing a "naturalization premium" for immigrants, but naturalization is selected: immigrants who naturalize differ in language, residence, employment, and motivation. We provide a quantitative meta-analysis of citizenship effects on immigrant earnings, synthesizing 60 preferred estimates from 31 studies. How a study separates the effect of citizenship from selection into citizenship-its identification strategy-explains more variation in estimates than destination country, citizenship regime, or any other study feature we code. Averaging published estimates with a multilevel random-effects model yields a pooled premium of 9.9% (95% CI 5.1 to 14.9), and 11.0% (95% CI 5.7 to 16.6) when pooling within study-country cells. But this average conceals sharp differences across research designs. The randomized encouragement study relying on a lottery to overcome selection implies a near-zero effect of 1.9% (95% CI -1.3 to 5.3); the regression-discontinuity study yields 11.3% (95% CI 5.2 to 17.8); estimates from policy reforms and within-unit panels are positive on average but too imprecise to distinguish from either zero or the pooled average; and observational instrumental-variable estimates average 53.0% (95% CI 27.6 to 83.5). Excluding observational instrumental-variable estimates reduces the pooled premium to 6.0% (95% CI 3.8 to 8.2). Reanalyzing the randomized trial data shows the same pattern: Experimental estimates are near zero, while an observational difference-in-differences comparison based on self-selected citizenship uptake implies a 9.6% gain (95% CI 4.0 to 15.5) four years post lottery, a bias standard pretrend tests do not detect. The published citizenship premium is positive, but its size and causal interpretation depend on research design.