1. A frequency based keyword extraction method utilizing a statistical measure, comprising: for at least one word in a document wherein said document comprises at least one keyword, computing a document frequency function of a number of times said at least one word occurs in said document wherein said document frequency is defined as a count of said word in said document divided by a count of a total number of words in said document; calculating an intra-document frequency confidence interval based on said document frequency; for said at least one word, computing a corpus frequency function representing a number of times said at least one word occurs in a corpus of documents excluding said document wherein said corpus frequency is defined as a count of said word in said corpus of documents divided by a count of total number of words in said corpus of documents; calculating a corpus frequency confidence interval based on said corpus frequency; identifying at least one common stop word according to a frequency threshold parameter; excluding said at least one common stop word; and thereafter testing a hypothesis by comparing a test statistic represented by said intra-document frequency confidence interval with a test statistic represented by said corpus frequency confidence interval, wherein a lower bound of said intra-document confidence interval is required to be greater than an upper bound of said corpus frequency confidence interval in order to thereby extract said at least one keyword from said document.