NUMCLUSTERS Subcommand (TWOSTEP CLUSTER command)

The NUMCLUSTERS subcommand specifies the number of clusters into which the data will be partitioned.

AUTO. Automatic selection of the number of clusters. Under AUTO, you may specify a maximum number of possible clusters. TWOSTEP CLUSTER will search for the best number of clusters between 1 and the maximum using the criterion that you specify. The criterion for deciding the number of clusters can be either the Bayesian Information Criterion (BIC) or Akaike Information Criterion (AIC). TWOSTEP CLUSTER will find at least one cluster if the AUTO keyword is given.

FIXED. User-specified number of clusters. Specify a positive integer.

Examples

TWOSTEP CLUSTER 
  /CONTINUOUS VARIABLES = INCOME
  /CATEGORICAL VARIABLES = GENDER RACE
  /NUMCLUSTERS AUTO 10 AIC
  /PRINT SUMMARY COUNT.

TWOSTEP CLUSTER uses the variables RACE, GENDER and INCOME for clustering. Specifications on the NUMCLUSTERS subcommand will instruct the procedure to automatically search for the number of clusters using the Akaike Information Criterion and require the answer to lie between 1 and 10.

TWOSTEP CLUSTER 
  /CONTINUOUS VARIABLES = INCOME
  /CATEGORICAL VARIABLES = RACE GENDER 
  /NUMCLUSTERS FIXED 7
  /PRINT SUMMARY COUNT.

Here the procedure will find exactly seven clusters.