SPSS® 12.0 Command Syntax Reference

SPSS-Format Data File
Files 13
An SPSS-format data file is a file specifically formatted for use by SPSS, containing both
data and the dictionary that defines the data. The dictionary contains names for the variables,
formats for reading and displaying values, and optional variable and value labels and
missing-value specifications. SPSS-format data files are created by using a SAVE or XSAVE
command during a session. On most operating systems, the default extension of a saved
SPSS-format data file is .SAV. An SPSS-format data file can also be a matrix file created with
the MATRIX=OUT subcommand on procedures that write matrices.
To retrieve an SPSS-format data file, use GET. SPSS-format data files speed processing
and are required as input for combining files during a session. For a discussion of the structure
of SPSS-format data files, see “SPSS Data File Structure” below.
SPSS Portable File
A portable file contains all of the data and dictionary information stored in the working data
file but is specially formatted for transporting files between installations with different
versions of SPSS (such as the PRIME, VAX, or HONEYWELL GCOS computers) or for
transporting files between SPSS, SPSS/PC+, and other software using the same portable file
format. Use IMPORT to read a portable file and EXPORT to save the working data file as a
portable file. On most operating systems, the default extension of a saved portable file is
.POR. Since a portable file needs conversion, it is always simpler to transport a file as an
SPSS-format data file whenever possible.
Working Data File
The working data file is the data file you build to use in the current session. You can retrieve
an SPSS-format data file using GET, which in effect makes a working copy of the specified
file. You can also build a new file with DATA LIST or other data definition commands.
The working data file is not created until SPSS encounters a command (usually a
procedure) that causes it to read the data (see Table 1). At that point, SPSS executes all of
the preceding data definition and transformation commands and the command that causes the
data to be read. The working data file is then available for further transformations and
procedures, and it remains available until replaced by a new working data file or until the end
of the session.
Some procedures can add variables to the working data file. Others, such as AGGREGATE
and procedures that write matrix materials, can replace the working data file.
Any transformations and statistical analyses that you request during a session are
performed on the working data file. Transformations performed during a session apply to the
working data file only. Changes to the file are lost if the working data file is erased or
replaced before you have saved it. See SAVE and XSAVE.
SPSS Data File Structure
An SPSS-format data file is a self-documented file containing data and descriptive information.
The descriptive information is called the dictionary. It contains variable names and