[Farm93]

 One problem with measuring it is that wearing the mask may not be the only, or even the primary, difference between the two groups.

Goose, that's true.

A person that wears masks 100% of the time is highly likely to engage in several other known efforts to reduce their chances of exposure.   While a person that doesn't wear a mask every will likely engage in any number of risky actions (parties, eating in restaurants, attending Notre Dame games, etc.)

Ultimately, even the mask itself alters behavior.   Whenever I do anything outdoors my mask is on.   It is annoying, and as a result I spend far less time outside of my home because wearing is not much fun.

So is it the mask? Is it my other risk reducing measures? Is it the mask's influence on my choices?  Hard to know which variables are most critical, but the easiest thing to do BY FAR is for the federal government to consistently tell everyone to wear masks all of the time and wear masks themselves whenever possible.

Everyone should be like POTUS-elect Joe and wear a mask.  

Wear masks until a vaccine is available, so we can all get back to something closer to normal ASAP.  How much does it help? Who cares really, by the time we can answer that question we should have a vaccine.

[Farm93]

 One problem with measuring it is that wearing the mask may not be the only, or even the primary, difference between the two groups.

Goose, that's true.

A person that wears masks 100% of the time is highly likely to engage in several other known efforts to reduce their chances of exposure.   While a person that doesn't wear a mask every will likely engage in any number of risky actions (parties, eating in restaurants, attending Notre Dame games, etc.)

Ultimately, even the mask itself alters behavior.   Whenever I do anything outdoors my mask is on.   It is annoying, and as a result I spend far less time outside of my home because wearing is not much fun.

So is it the mask? Is it my other risk reducing measures? Is it the mask's influence on my choices?  Hard to know which variables are most critical, but the easiest thing to do BY FAR is for the federal government to consistently tell everyone to wear masks all of the time and wear masks themselves whenever possible.

Everyone should be like POTUS-elect Joe and wear a mask.  

Wear masks until a vaccine is available, so we can all get back to something closer to normal ASAP.  How much does it help? Who cares really, by the time we can answer that question we should have a vaccine.