They say: Sick should wear masks, well people don't need to, but masks are collective act:
If sick don't, well should
If everyone wears masks, sick wear them. If nobody wears masks, they don't
If you wear a mask, people will be comfortable wearing a mask with you. If not, not
If sick don't, well should
If everyone wears masks, sick wear them. If nobody wears masks, they don't
If you wear a mask, people will be comfortable wearing a mask with you. If not, not
Also
The standard advice is the usual "independence" assumption where each decision is made independently.
Also, the case of "sick person doesn't wear mask what is the effect of well person wearing or not wearing mask", is not statistically significant relative to all cases.
Also, the case of "sick person doesn't wear mask what is the effect of well person wearing or not wearing mask", is not statistically significant relative to all cases.
Also it seems that the reason people are critical of masks is because they don't absolutely guarantee safety. So that should be part of the instructions. A factor of 5 reduction in risk (order of magnitude) is significant theguardian.com/world/2020/feb…
