"A common mistake in meta-analysis is to combine apples and oranges. If apples work but oranges don’t, combining studies in a single average figure may lead to the conclusion that apples don't work. "
@trishgreenhalgh @Globalbiosec @DFisman @doctorahmad75
https://theconversation.com/yes-masks-reduce-the-risk-of-spreading-covid-despite-a-review-saying-they-dont-198992
I've been posting a bit about this, and I think this article, from November 2019, gives a good intro to the subject.
https://www.aclu.org/news/free-speech/americas-mask-bans-in-the-age-of-face-recognition-surveillance