The question over Google using click data, such as how many people click on your site from a Google result, how many people click click the back button and so on, as it relates to ranking web pages in Google - is nothing new. We discussed it at least three times.
But this time we have a small and obscure comment from a Google representative on the matter. A Google Webmaster Help thread has a comment from Googler, JohnMu, not saying much on it, but you tell me what he means:
I can tell you for sure that anyone visiting your site a few dozen times and hitting the back button on their browser is not going to impact your site's crawling, indexing, or ranking at Google. That wouldn't make much sense and would be too easy to abuse :-).
So, John here clearly talks about "hitting the back button on their browser." He goes on to say that it won't "impact your site's crawling, indexing, or ranking at Google," if done a "few dozen times." Now, it is not clear if it is done a few hundred thousand times if it will make a difference or not. I don't think we can use this as a confirmation from Google based on this statement on if Google uses this data in their ranking algorithm or not. But who knows.
Forum discussion at Google Webmaster Help.