Why might the estimated number of results change when going from page 1 to page 2?

How reliable is the site: query and why does the total count sometimes change from page 1 to page 2? Blind Five Year Old, SF, CA Have a question? Ask it in our Webmaster Help Forum: groups.google.com Want your question to be answered on a video like this? Follow us on Twitter and look for an announcement when we take new questions: twitter.com More videos: www.youtube.com Webmaster Central Blog: googlewebmastercentral.blogspot.com Webmaster Central: www.google.com