I looked for the methodology for this study, I found it and it it seems well thought out, but there is not enough detail on how they removed selection bias to k

I looked for the methodology for this study, I found it and it it seems well thought out, but there is not enough detail on how they removed selection bias to know for sure if these numbers are solid. However, everything they do say about the methodology points to it being a competent and properly run study, it's just that it is extremely hard to gather this data online in a way that ends up being representative even if your methods are sound. I would like to know more about the details of the study, but right now I would say it's reasonable to believe that there is a moderately high degree of certainty that these numbers are accurate (but of course the study was limited to the UK).