XieBeni index (XB) [47] measures

\({XB=\frac {\sum \limits _{k=1}^{K}\sum \limits _{i=1}^{n} D^{2}(z_{k}, x_{i})}{ n \times \min _{k\neq l}\{D^{2}(z_{k}, z_{l})\}}} \)

Minimisation

the quotient between the total
 
variance and the minimum
 
separation of the elements
 
in the clusters.
 
Overall cluster deviation (Dev) [48]

\(Dev= \sum \limits _{k=1}^{K} \sum \limits _{x_{i} \in C_{k}} D(z_{k}, x_{i})\)

Minimisation

is defined as the overall summed
 
distances between genes and their
 
corresponding cluster medoid.
 
Cluster separation (Sep) [49] is

\( Sep= \frac {2}{K(K1)}\sum \limits _{k=1}^{K} \sum \limits _{j=1, j\not =i}^{K} D^{2}(z_{i}, z_{j})\)

Maximization

defined as intercluster distances
 
between cluster medoids.
 