16. The computer program product as in claim 15 wherein processing a plurality of user social networking profiles to identify coincident keywords further includes: processing the measured degree, the determined ratio and the correlation index to determine a percentage of co-occurrence for each of the keywords; and determining, using the percentage of co-occurrence, a correlation ratio indicating how often a coincident keyword is present when another coincident keyword is present.
15. The computer program product as in claim 11 wherein computing the frequency with which a keyword appears in conjunction with another keyword in one or more of the multitude of user profiles for the data expansion model further includes: measuring the degree to which the two keywords tend to occur together; determining a ratio indicating the frequency with which the two keywords appear together; and determining a correlation index indicating the likelihood that users interested in one of the keywords will be interested in the other keyword, as compared to an average user profile.