Income and Inequality in the Aztec Empire: A Replication of Alfani and Carballo (Nature Human Behaviour, 2023)

Alfani and Carballo (2023) estimate income inequality in the Aztec Empire around 1492. Their preferred estimate gives a Gini index of 50.4. They conclude that inequality was high even beforethe Spanish conquest. First, I confirm that the main outcomes are computationally reproduciblefrom the analysis data provided in the replication package. Second, I examine two inconsistencies.Third, I test the robustness reproducibility of the relationship between population density andper capita income through eight different robustness tests, confirming a positive and statisticallysignificant relationship but with considerable variation in the point estimates. Finally, I usethese estimates as inputs for robustness measures of the main outcomes. The results support thequalitative conclusion that inequality and extraction were substantial before the Spanish conquest.Their exact magnitudes, however, depend on modelling choices and should be interpreted asapproximate historical estimates rather than precise measurements.