> Let’s take a look at the recent Cochrane review. This is a review only of controlled studies – the kind of study that is most likely to underestimate the effect of mask-wearing.
So the author would rather use studies with no control arm? How do you measure effectiveness without one in a scientific way? It's how we measure all interventions.
@weebull
That paragraph is not about which kind of studies is better or worse. But pointing out that the review was very selective on which studies to include. Which is a red flag. I think.