Ranked Adjusted Rand ( RAR ), Adjusted Rand ( HA ) and Wallace ( W ) indices for the comparison of emm type with PFGE clusterings using different Dice dissimilarity thresholds. Dice dissimilarity is in a 0–100 scale. The plot in the top indicates the number of PFGE clusters originated with the respective threshold, while the number of emm types is always 12. The minimum threshold studied, 1, does not originate 325 clusters because there are sets of isolates whose PFGE band patterns have a Dice dissimilarity of 0. W(emm-PFGE) is the probability that a pair of isolates is in the same PFGE cluster knowing that they have the same emm type. Analogously, W(PFGE-emm) is the probability that a pair of isolates has the same emm type knowing that they are in the same PFGE cluster. HA reflects the evolution of both Wallace indices. The plateau of maximum HA, between the thresholds of 28 and 41, is a region of compromise where both Wallace indices are high. The curve of RAR values shows a more complex behaviour, with a plateau of maximum values between the thresholds of 20 and 29, and a significant decrease between 29 and 41, where HA is nearly constant.