KEI (Keyword Effectiveness Index)
Keyword effectiveness index: A mathematical representation of the popularity of a keyword measured in number of searchers (demand), compared to its popularity measured as the number of pages in a search engines index (supply).
KEI is a statistical formulation that reveals the most effective keyword phrases and terms to use in optimizing your web pages for. Efficiency can be many things. According to KEI, it is efficient to optimize for keywords that have many searchers, but only a few competing pages.
The lower the KEI, the more popular your keywords are, and the less competition they have. That means that you might have a better chance of getting to the top in the search engines and receive a good number of searchers for your effort.
The Theme Zoom Krakken and The Last Keyword Tool technology takes KEI to a whole other level, and is worthy of consideration for any serious SEO who wants to tweak and enhance the 'low hanging fruit' keyword research methods of the past turning them into the process of swallowing your market whole.
Also See Network Empire