The sequence similarity score is a relative evaluation based on the Blosum62 matrix scores, whereas the Jaccard similarity score is an absolute measure of the similarity between two sequences where identical sequences return a score of one. It should be noted, however, that the number of matches grows more quickly than the size of the set-i.e. the numerator of the Jaccard score grows more quickly than the denominator. This means that a comparatively low Jaccard score can still indicate a reasonable amount of similarity. Very roughly, for the 2-mers, a Jaccard score of 0.06 is the expected value for two random sequences of length 50, and it is significantly lower than that for the 3-mers.