SPSS® 12.0 Command Syntax Reference

MATRIX Subcommand
ALSCAL 113
MATRIX reads SPSS matrix data files. It can read a matrix written by either PROXIMITIES or
CLUSTER.
• Generally, data read by ALSCAL are already in matrix form. If the matrix materials are in the
working data file, you do not need to use MATRIX to read them. Simply use the VARIABLES
subcommand to indicate the variables (or columns) to be used. However, if the matrix materials
are not in the working data file, MATRIX must be used to specify the matrix data file that
contains the matrix.
• The proximity matrices ALSCAL reads have ROWTYPE_ values of PROX. No additional
statistics should be included with these matrix materials.
• ALSCAL ignores unrecognized ROWTYPE_ values in the matrix file. In addition, it ignores
variables present in the matrix file that are not specified on the VARIABLES subcommand
in ALSCAL. The order of rows and columns in the matrix is unimportant.
• Since ALSCAL does not support case labeling, it ignores values for the ID variable (if
present) in a CLUSTER or PROXIMITIES matrix.
• If split-file processing was in effect when the matrix was written, the same split file must
be in effect when ALSCAL reads that matrix.
• The specification on MATRIX is the keyword IN and the matrix file in parentheses.
• MATRIX=IN cannot be used unless a working data file has already been defined. To read
an existing matrix data file at the beginning of a session, first use GET to retrieve the matrix
file and then specify IN(*) on MATRIX.
IN (filename) Read a matrix data file. If the matrix data file is the working data file, specify
an asterisk in parentheses (*). If the matrix data file is another file, specify
the filename in parentheses. A matrix file read from an external file does not
replace the working data file.
Example
PROXIMITIES V1 TO V8 /ID=NAMEVAR /MATRIX=OUT(*).
ALSCAL VAR=CASE1 TO CASE10 /MATRIX=IN(*).
• PROXIMITIES uses V1 through V8 in the working data file to generate a matrix file of Euclidean
distances between each pair of cases based on the eight variables. The number of
rows and columns in the resulting matrix equals the number of cases. MATRIX=OUT then
replaces the working data file with this new matrix data file.
• MATRIX=IN on ALSCAL reads the matrix data file, which is the new working data file. In
this instance, MATRIX is optional because the matrix materials are in the working data file.
• If there were 10 cases in the original working data file, ALSCAL performs a multidimensional
scaling analysis in two dimensions on CASE1 through CASE10.
Example
GET FILE PROXMTX.
ALSCAL VAR=CASE1 TO CASE10 /MATRIX=IN(*).
• GET retrieves the matrix data file PROXMTX.