Ok, I just found the methodology link in the giant footer and I've been looking for something like it for a while. Call me stupid or whatever if you like. It's an ok link, but I really think you should expand it to go into more depth and include more of what we've been discussing in this thread. Assume a basic understanding of statistics, but include all of the relevant details about sampling methods. Then you can link to a separate FAQ page and probably include a link to this editorial or something similar http://www.vgchartz.com/article/82746/editorial-why-it-is-so-easy-to-blame-vgchartz/ intended for some of the stupider questions.
I really think including the Methodology page more prominently in the site design would not be overkill and would help a lot, since it's an important element of the site. I would actually include it somewhere in the header, but simply bolding the link at the bottom of the charts would make it more noticeable.







