A study using Ontario's 34 Public Health Units over the course of two months found that wearing a mask can have a significant impact on the spread of COVID-19.

No argument there, anyone would be worried if their surgeon showed up in the operating room without a mask on, but the economists go a little further and claim mask mandates are the reason. They statistically associate mandates with a 25 percent reduction in COVID-19 cases.

The findings have not been peer-reviewed but since this is not science peer review wouldn't make much difference. If you write a criticism of a criticism of Proust you can get it peer reviewed and into a journal, but it isn't making much of a difference to the public, but the because the economists are making public health policy suggestions, the numbers matter. So let's take a look.


They believe that mandating indoor masks nationwide in early July could have reduced the weekly number of new cases in Canada up to 40 percent in mid-August.  How does anyone know what could have happened in an alternate universe? It's not possible, but we see cosmic claims about how much virtual money could be saved any time there is a call to pass some new law for something or other. The confounder in their analysis is Ontario itself; they were already wearing masks based on nothing but being told that wearing them prevents the spread of coronvirus. How would a law have made 40 percent fewer cases when so few were in public spaces indoors without masks? 

Yet that is the foundation of their 40 percent conclusion. They did a simple comparison of trends in areas that mandated masks earlier than later. Using brute force statistics they stated that mask mandates reduced new cases up to 31 percent compared to those without a mask mandate.

It's not painting an accurate picture of the positive impact of masks because it frames the law mandating the mask as the real victor rather than the mask. In August the county in Pennsylvania where I grew up had zero cases of COVID-19. Would all of us moving there mean we can't get COVID-19? Statistics could show that. Should they be mandated to wear masks based on Manhattan statistics? A study could show that. Should Manhattan not wear masks because a rural county had no cases? Of course not, but simplistic framing could allow all of those arguments.

COVID-19 is still happening because it's a powerful virus. It may only appear to be happening in some spots more than others, and we can draw spurious correlations from anything to anything if we try, but they are happening everywhere. The difference in parts of Ontario may be because more people most likely to get it already got it, it may be because they wore masks without a government mandate.

We don't need laws to tell us to wear a mask in America, so it is unlikely it will make more Canadians do it either. It will instead breed more rebellion. And that is not going to be helpful.