While the study provides a detailed methodological framework for analyzing income convergence among Spanish provinces, it does not sufficiently account for external factors that could influence income levels, such as regional policies, infrastructure investments, or demographic changes. The authors assume that the transition probabilities between income states are solely driven by historical income data, which may oversimplify the complex dynamics of economic convergence. This omission could lead to biased estimates of long-term income distributions and convergence speeds, particularly in the context of the COVID-19 pandemic, which introduced unprecedented economic shocks. Without addressing these potential biases, the conclusions drawn about the impact of COVID-19 on income convergence may be overstated or misleading. A more rigorous approach would involve incorporating additional control variables or employing sensitivity analyses to test the robustness of the findings.
