The study is biased in that it pulled samples from a grocery store based on people opting in. If I walk in to a grocery store and someone offers to give me thi

The study is biased in that it pulled samples from a grocery store based on people opting in. If I walk in to a grocery store and someone offers to give me this test, I am going to say no for 2 reasons: 1) I have not been sick since last fall 2) I don't want to take additional risk getting bloodwork done by someone who is testing people for covid19 antibodies. I want to take a little risk as possible and return home to my family. So basically this test only possibly grabs people who are willing to risk going to the grocery store rather than having food delivered, and who are willing to take on additional risk of getting tested. It is even less likely that a person not taking risk, who never had any symptoms would get tested than a person who had had symptoms. The entire premise that this represents the population as a whole is completely flawed.