3. PERFORMANCE ANALYSIS TOOLS › 3.3 Data Clustering Analysis › 3.3.3 Standard Output › 3.3.3.6 Cluster Index Analysis Graph

3.3.3.6 Cluster Index Analysis Graph

This graph uses two different formats, depending on data
volumes and the print line size specified in the MICF
options:

   o BLOCK chart
   o Horizontal bar (HBAR chart)

In either case, one entry is made for each cluster
selected and the clustering index value is displayed.

                                           Data Clustering Analysis
                                            Cluster Index Analysis
                                          For: Monday, June 23, 2003
 
                            Analysis Performed Using Variables: JOBTCBTM JOBEDASD
 
Cluster Number                                                                                  Cluster Index
                                                                                                          Sum
          |
      1   |                                                                                              0.00
          |
     10   |*****************                                                                             0.34
          |
     11   |***************************************                                                       0.77
          |
     14   |************************************************************                                  1.19
          |
     15   |***********************************************                                               0.95
          |
     16   |****************************************                                                      0.80
          |
     17   |*************************************************************************************         1.69
          |
     23   |*************************************************************************************         1.70
          |
     24   |*************************************************                                             0.98
          |
          -----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
              0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70
 
                 Cluster Index. Sparse Clusters Have Been Excluded

 Figure 3-38.  Cluster Index Analysis graph

The clustering index value is the Root Mean Square (RMS) of
the distances of all feature values within the cluster.  As
stated previously, this is a relative measurement of cluster
performance and "goodness of fit" of the data, with respect
to the cluster centroid values.  A lower value represents a
better performing cluster, indicating more tightly formed
clusters and fewer outlying values.

This graph is a simple, yet effective to quickly evaluate the
overall performance of the clustering operation and can be
used to communicate this performance to non-technical
personnel.