KEI Keyword efficiency Index alternative

This is a new concept relatively and seos are following this while optimizing the site. When you build a site to attract visitors through search engines, so that they would click and you get some money, you have to optimize and aim at some keywords. But some keywords are very competetive and highly searched while some are less competetive and sparsely searched. Now which keyword we have to aim at.
so, collect all keywords with information that how many searches were made on this keyword per day. This can be obtained from yahoo pixelfast, as they give searches in last month against that keyword. From this you derive per day searches. Now you enter this keyword in quotes and without quotes in the yahoo search engin and get number of pages offering page for this. Now, when you derive a ration between the number of searches per day to total results fetched , the ratio is KEI. This should be high . If this is low, the competetion is very high and better search for other keywords.
While selecting keywords let us not concentrate only on oneword two word keywords. a lengthy keyword would also be useful to build. One better way than KEI analysis is just go on collecting the key words that brought visitors to your site. Tbese are the LIFE LINES for your site. Just concentrate on these and imrove your site. The objective is that the searching person should get more easily you page, when he next searches with the same keyword. This is called LIFE LINE IMPROVEMENT TECHNIQUE. This is based on known devil is better than unknown God.
In this KEI analyis , so many ifs and butts are there and it will never give relaiable conclusion. In this life line technique, the visitors should never miss you and you will be more prominent day by day for those all keywords that brought visitors to you. These set of keywords are your own keywords.