The Mask Studies You Should KnowFirst, a primer on the levels of the different levels of quality of research and the “Hierarchy of evidence.” Not all studies are equal in their level of certainty or quality, but the absolute most reliable and most certainty we can get usually comes from Systematic Reviews and Meta-Analysis of Randomized Control Trials. See the chart below from the Center for Evidence Based Medicine:Luckily we have the highest possible evidence we can get on the effectiveness of masks. A Systematic Review of Randomized Control Trials. Cochrane Library (widely considered a gold standard in evidence based...
