The VARCLUS Procedure

The following items are displayed for each cluster solution unless the NOPRINT or SUMMARY option is specified. The CLUSTER SUMMARY table includes the following columns:

• the Cluster number

• Members, the number of members in the cluster

• Cluster Variation of the variables in the cluster

• Variation Explained by the cluster component. This statistic is based only on the variables in the cluster rather than on all variables.

• Proportion Explained, the result of dividing the variation explained by the cluster variation

• Second Eigenvalue, the second largest eigenvalue of the cluster. This is displayed if the cluster contains more than one variable and the CENTROID option is not specified

PROC VARCLUS also displays the following:

• Total variation explained, the sum across clusters of the variation explained by each cluster

• Proportion, the total explained variation divided by the total variation of all the variables

The cluster listing includes the following columns:

• Variable, the variables in each cluster

• R square with Own Cluster (the squared correlation of the variable with its own cluster component), and R square with Next Closest (the next highest squared correlation of the variable with a cluster component). Own Cluster values should be higher than the R square with any other cluster unless an iteration limit is exceeded or you specify the CENTROID option. Next Closest should be a low value if the clusters are well separated.

• 1R**2 Ratio, the ratio of one minus the value in the Own Cluster column to one minus the value in the Next Closest column. The occurrence of low ratios indicates well-separated clusters.

If the SHORT option is not specified, PROC VARCLUS also displays the following tables:

• Standardized Scoring Coefficients, standardized regression coefficients for predicting cluster components from variables

• Cluster Structure, the correlations between each variable and each cluster component

• Inter-Cluster Correlations, the correlations between the cluster components

If the analysis includes partitions for two or more numbers of clusters, a final summary table is displayed. Each row of the table corresponds to one partition. The columns include the following:

• Number of Clusters

• Total Variation Explained by Clusters

• Proportion of Variation Explained by Clusters

• Minimum Proportion (of variation) Explained by a Cluster

• Maximum Second Eigenvalue in a Cluster

• Minimum R square for a Variable

• Maximum 1R**2 Ratio for a Variable