SPSS® 12.0 Command Syntax Reference

CLUSTER 237
MEDIAN Median clustering (WPGMC). Squared Euclidean distances are commonly
used with this method.
WARD Ward’s method. Squared Euclidean distances are commonly used with this
method.
Example
CLUSTER V1 V2 V3
/METHOD=SINGLE COMPLETE WARDS.
• This example clusters cases based on their values for variables V1, V2, and V3, and uses
three clustering methods: single linkage, complete linkage, and Ward’s method.
SAVE Subcommand
SAVE allows you to save cluster membership at specified solution levels as new variables in
the working data file.
• The specification on SAVE is the CLUSTER keyword, followed by either a single number
indicating the level (number of clusters) of the cluster solution or a range separated by a
comma indicating the minimum and maximum numbers of clusters when membership of
more than one solution is to be saved. The number or range must be enclosed in
parentheses and applies to all methods specified on METHOD.
• You can specify a rootname in parentheses after each method specification on the METHOD
subcommand. CLUSTER forms new variable names by appending the number of the cluster
solution to the rootname.
• If no rootname is specified, CLUSTER forms variable names using the formula CLUn_m,
where m increments to create a unique rootname for the set of variables saved for one
method and n is the number of the cluster solution.
• The names and descriptive labels of the new variables are displayed in the procedure
information notes.
• You cannot use the SAVE subcommand if you are replacing the working data file with
matrix materials (see “Matrix Output” on p. 240).
Example
CLUSTER A B C
/METHOD=BAVERAGE SINGLE (SINMEM) WARD
/SAVE=CLUSTERS(3,5).
• This command creates nine new variables: CLU5_1, CLU4_1, and CLU3_1 for BAVERAGE,
SINMEM5, SINMEM4, and SINMEM3 for SINGLE, and CLU5_2, CLU4_2, and CLU3_2 for
WARD. The variables contain the cluster membership for each case at the five-, four-, and
three-cluster solutions using the three clustering methods. Ward’s method is the third
specification on METHOD but uses the second set of default names since it is the second
method specified without a rootname.
• The order of the new variables in the working data file is the same as listed above, since
the solutions are obtained in the order from 5 to 3.
• New variables are listed in the procedure information notes.