Reliance on Surname-Grouped Estimator for Intergenerational Links
The study uses surnames to create 'pseudo-links' between ancestors and descendants. While common in historical studies, this method has known biases (upward or downward) because it's not individual-based. The paper acknowledges it's a mix of 'inclusive' and 'leave-out' cases without clear priors on bias direction and discusses that persistent differences between surnames can drive up intergenerational correlation.
Selection Bias due to Data Availability and Migration
The dataset only includes surnames present in both 1427 and 2011 Florence, meaning families who migrated away or whose surnames died out are excluded. This can introduce selection bias, as surviving and missing families may have different characteristics and mobility patterns, potentially affecting the generalizability of the findings, despite robustness checks.
Privacy Restrictions Limiting Sample Representativeness
To comply with privacy rules, surnames with fewer than five occurrences in 2011 were excluded. This could potentially skew the sample, as less common surnames might represent different socioeconomic groups or mobility experiences, despite the authors arguing the impact is negligible.
Generalizability to Other Regions/Societies
The study focuses exclusively on Florence. While the authors argue that 15th-century Florence was comparable to other pre-industrial Western European societies in terms of inequality, this remains an inference. The specific institutional and cultural context of Florence might limit the direct applicability of these very long-run persistence findings elsewhere.
Strong Assumption in Robustness Check for Migrants
In a robustness check to address potential bias from missing families (migrants), the authors assume that for these families, the intergenerational elasticity is zero, meaning they completely broke free from socioeconomic inheritance. The paper explicitly states this is the 'most unfavorable assumption' and 'not very plausible,' indicating a significant, albeit necessary for the test, simplification.