Explaining international differences in excess mortality due to Covid-19

Many explanations have been advanced for why the frequency of deaths associated with Covid-19 varied so much across countries. Previous work has provided evidence that numerous social, economic, and environmental factors correlate with Covid-19 outcomes. One problem researchers face in identifying which of these explanations are best able to explain cross-country variation is that the number of these explanations is too large to be usefully included in a single regression model. This paper uses Bayesian Model Averaging (BMA) to address this problem, focusing on excess mortality to ensure meaningful comparisons across countries. The results suggest that a key determinant of countries' success in containing Covid-19 has been the strength of the Rule of Law. We also find evidence that rainfall and seaborders are key potential explanations for differences in excess mortality.