The most interesting thing about the study, from my perspective, was that it sought to understand what effect lockdowns, border closures, and widespread testing have in terms of decreasing the number of covid deaths. Although correlation does not automatically imply causation, if there is a lack of correlation, then that strongly suggests a lack of causation, or at least, that any causative relationship that does exist is extremely weak. And considering the amount of money, effort, and resources that have been poured in to lockdowns this year, and that continue to be poured in to them right now, it would be pretty disappointing if lockdowns had such a minimal effect that there was no noticeable impact on mortality whatsoever. Am I right?
But I get ahead of myself. The study chose to limit itself to looking at the 50 countries with the most recorded cases of covid-19 as of the 1st of April 2020. My interpretation is that they chose the top 50 most affected countries, rather than looking at all 195 countries, due to resource constraints. Data was gathered up to the 1st of May 2020. All information gathered was in the form of publicly available facts and figures. Data gathered included information about covid, income level, gross domestic product, income disparity, longevity, BMI (Body Mass Index), smoking, population density, and a bunch of other things that the researchers thought might be interesting to look at. The authors received no outside funding and reported no conflicts of interest.