What is KEI?
Measuring and comparing the demand for your keyword (Daily World Searches), against the number of Web pages that include it (Competition) is a recommended approach to detect the best keywords. The resulting ratio value, KEI or ‘Keyword Effectiveness Index' provides an idea of how important a specific keyword is.
{If you are technical: The formula for KEI is KEI = (DS^2/C) = (DS/C * DS). The KEI ranges from 0 to over 400.
< 0,001 = Poor keyword
0,001-0,010 = Good Keyword
0,010-0,100+ = Excellent Keyword
The higher the KEI ratio, the more popular your keywords are (more people are searching using those keywords), and the less competition they have (fewer websites that would come up as relevant results in search engine results pages}.
Keywords with the highest KEI combine the best popularity with less competition, meaning higher rankings if you use them.
