SPSS® 12.0 Command Syntax Reference

242 CLUSTER
Split Files
• VARNAME_ is a string variable that takes the values VAR1, VAR2 ...VARn, to correspond
to the names of the distance variables in the matrix (VAR1, VAR2 ... VARn, where n is the
number of cases in the largest split file). The numeric suffix for the variable names is consecutive
and may not be the same as the actual case number.
• The remaining variables in the matrix file are the distance variables used to form the
matrix. The distance variables are assigned variable labels in the form of CASE m to
identify the actual number of each case.
• When split-file processing is in effect, the first variables in the matrix data file are the split
variables, followed by ROWTYPE_, the case-identifier variable or ID, VARNAME_, and the
distance variables.
• A full set of matrix materials is written for each split-file group defined by the split variables.
• A split variable cannot have the same name as any other variable written to the matrix
data file.
• If split-file processing is in effect when a matrix is written, the same split file must be in
effect when that matrix is read by any procedure.
Missing Values
Example
Missing-value treatment affects the values written to a matrix data file. When reading a
matrix data file, be sure to specify a missing-value treatment on CLUSTER that is compatible
with the treatment that was in effect when the matrix materials were generated.
DATA LIST FILE=ALMANAC1 RECORDS=3
/1 CITY 6-18(A) POP80 53-60
/2 CHURCHES 10-13 PARKS 14-17 PHONES 18-25 TVS 26-32
RADIOST 33-35 TVST 36-38 TAXRATE 52-57(2).
N OF CASES 8.
CLUSTER CHURCHES TO TAXRATE
/ID=CITY
/MEASURE=EUCLID
/MATRIX=OUT(CLUSMTX).
• CLUSTER reads raw data from file ALMANAC1 and writes one set of matrix materials to
file CLUSMTX.
• The working data file is still the ALMANAC1 file defined on DATA LIST. Subsequent commands
are executed on ALMANAC1.