With what sources of information do the results compare?
I believe, its all about trusted indexes(not about to type its name here so it wouldn't look like an advertisement) and forums, I mean astounding ones, such as bitcointalk!
Perhaps, but is it written on a site, if there is an official information?
Can hardly insist on it, but you may check it via Xwin platform, they definitely pay attention to all of the information, around its sphere.