15. The non-transitory computer-readable storage medium of claim 13 , wherein one weight coefficient is associated with each of the targeted subset count scores, the frequency normalization scores, and the distribution scores.
15. The non-transitory computer-readable storage medium of claim 13 , wherein one weight coefficient is associated with each of the targeted subset count scores, the frequency normalization scores, and the distribution scores. 16. The non-transitory computer-readable storage medium of claim 15 , wherein the weight coefficients are pre-determined based on a desired relative importance of each of the targeted subset count scores, the frequency normalization scores, and the distribution scores.