A couple days back I posted a scatter plot that suggested that social democracies and developmental states had lower levels of COVID-19 prevalence. Here it is again (updated by several days).

I got a lot of feedback on this, asking if there were other factors that I’m leaving out. I’m certain that we don’t have good models of the epidemiology of COVID-19, so I’m sure that the answer is “yes.” But was able to add in a couple of control variables to see if they affect those results.

• Perhaps I should measure “island” comprehensively, coding Japan and the UK and Ireland as islands too instead of just Australia and New Zealand.
• What about the differences in seasons between northern and southern hemispheres?
• What about population density explaining low rates in Scandinavia and Australia?
• No one said this explicitly, but lots of people think that South Korea and Japan are just monoethnic societies that are better able to enforce social compliance.
• Could this be about level of economic development, or spending on health?

I dumped all of those variables in a series of OLS regressions with COVID-19 rates as the dependent variable, predicted by the Index of Social Democracy from Lane Kenworthy, a developmental state dummy, and various combinations of the rest. Here are coefficients plus 90% confidence intervals for all of these models.

We shouldn’t interpret too much from these results. The data are incomplete on case loads, and the sample size is just 21. But the findings are still quite provocative.