Ranking factors that aren't ranking factors

The phrase Ranking Factor is applied liberally to many things that aren’t actually ranking factors. On occasion, as in the case of Facebook likes, the SEO industry has clearly got it wrong. But what about the other factors that are based on patents, research papers and reasonable observations?  It can seem contradictory to know something is necessary to rank well in the search engines while Googlers say it is not a ranking factor. The following may sound like a contradiction but the surprising truth is that some factors necessary to rank are not always ranking factors.  Understanding the difference will make you a better Internet marketer.

This article discusses an important part of how search engines produce a search ranking, including details I've never heard a search engineer talk about.  http://www.martinibuster.com/search-algorithms/ranking-factors/