The right one shows their
silhouettes. In the silhouette, a large si (almost 1) suggests that the corresponding observations
are very well clustered, a small si (around 0) means that the observation lies between two clusters,
and observations with a negative si are probably placed in the wrong cluster. Since the average Si
are respectively 0.81 and 0.62 in the above silhouette, the identied two clusters are well clustered.