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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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1596 TWOSTEP CLUSTER<br />

Example<br />

TWOSTEP CLUSTER<br />

/CATEGORICAL VARIABLES = RACE GENDER CITIZEN<br />

/CONTINUOUS VARIABLES = INCOME<br />

/HANDLENOISE 25<br />

/PRINT SUMMARY COUNT.<br />

This tells TWOSTEP CLUSTER to cluster the categorical variables RACE, GENDER and<br />

CITIZEN, and the numeric variable INCOME. If the CF tree fills, a noise leaf is constructed<br />

from cases whose leaves contain fewer than 25 percent of the cases contained by the largest<br />

leaf. The CF tree is then re-grown, ignoring the noise leaf. After the tree is re-grown, cases<br />

from the noise leaf are checked to see if they fit any of the leaves in the new tree. Any cases<br />

that still do not fit are discarded as outliers. Summary statistics by cluster and cluster frequencies<br />

are output in tables.<br />

INFILE Subcommand<br />

The INFILE subcommand causes TWOSTEP CLUSTER to update a cluster model whose CF<br />

Tree has been saved as an XML file with the OUTFILE subcommand and STATE keyword.<br />

The model will be updated with the data in the active file. The user must supply variable<br />

names in the active file in the order they are stored in the XML file. TWOSTEP CLUSTER will<br />

update the cluster model in memory only, leaving unaltered the XML file.<br />

• If the INFILE subcommand is given, TWOSTEP CLUSTER will ignore the CRITERIA,<br />

DISTANCE, HANDLENOISE and MEMALLOCATE subcommands, if given.<br />

MEMALLOCATE Subcommand<br />

The MEMALLOCATE subcommand specifies the maximum amount of memory in megabytes<br />

(MB) that the cluster algorithm should use. If the procedure exceeds this maximum, it will<br />

use the disk to store information that will not fit in memory.<br />

• The minimum value you can specify is 4. If this subcommand is not specified, the default<br />

value is 64MB.<br />

• Consult your system administrator for the largest value you can specify on your system.<br />

MISSING Subcommand<br />

The MISSING subcommand specifies how to handle cases with user-missing values.<br />

• If this subcommand is not specified, the default is EXCLUDE.<br />

• TWOSTEP CLUSTER deletes any case with a system-missing value.<br />

• Keywords EXCLUDE and INCLUDE are mutually exclusive. Only one of them can be<br />

specified.<br />

EXCLUDE Exclude both user-missing and system-missing values. This is the default.<br />

INCLUDE User-missing values are treated as valid. System-missing values cannot be<br />

included in the analysis.

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