I used to work on survey designs in my old job. I am having a hard time coming up with a way that they could possibly control for selection bias. We are in the

I used to work on survey designs in my old job. I am having a hard time coming up with a way that they could possibly control for selection bias. We are in the middle of a pandemic, the people willing to risk leaving their homes to get tested is going to be highly skewed towards individuals that believe they have already had the infection. It's possible that they asked the participants about this, and adjusted their weights accordingly, but considering that this study shares authors with the Santa Clara study, and that study did not control for selection bias, I have my doubts.