SPSS® 12.0 Command Syntax Reference

Matrix Input
DISCRIMINANT 483
records in the matrix materials represent within-cell data, and separate covariance
matrices are written to the file. When the matrix file is used as input for a subsequent
DISCRIMINANT procedure, at least one of these specifications must be used on that
DISCRIMINANT command.
• DISCRIMINANT can read correlation matrices written by a previous DISCRIMINANT
command or by other procedures. Matrix materials read by DISCRIMINANT must contain
records with ROWTYPE_ values MEAN, N or COUNT (or both), STDDEV, and CORR.
• If the data do not include records with ROWTYPE_ value COUNT (unweighted number of
cases), DISCRIMINANT uses information from records with ROWTYPE_ value N (weighted
number of cases). Conversely, if the data do not have N values, DISCRIMINANT uses the
COUNT values. These records can appear in any order in the matrix input file with the
following exceptions: the order of split-file groups cannot be violated and all CORR
vectors must appear consecutively within each split-file group.
• If you want to use a covariance-type matrix as input to DISCRIMINANT, you must first use
the MCONVERT command to change the covariance matrix to a correlation matrix.
• DISCRIMINANT can use a matrix from a previous data set to classify data in the working
data file. The program checks to make sure that the grouping variable (specified on
GROUPS) and the predictor variables (specified on VARIABLES) are the same in the
working data file as in the matrix file. If they are not, the program displays an error
message and the classification will not be executed.
• 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.
Format of the Matrix Data File
• The matrix data file has two special variables created by the program: ROWTYPE_ and
VARNAME_. Variable ROWTYPE_ is a short string variable having values N, COUNT,
MEAN, STDDEV, and CORR (for Pearson correlation coefficient). The variable
VARNAME_ is a short string variable whose values are the names of the variables used to
form the correlation matrix.
• When ROWTYPE_ is CORR, VARNAME_ gives the variable associated with that row of the
correlation matrix.
• Between ROWTYPE_ and VARNAME_ is the grouping variable, which is specified on the
GROUPS subcommand of DISCRIMINANT.
• The remaining variables are the variables used to form the correlation matrix.