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> Overview
of SPSS
>
Interface
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Statistical
Package
for the
Social
Sciences
Syntax for INTERFACE Commands
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Interface commands control the creation
of SPSS system files. A system file
contains all data and descriptive information that
defines the data (e.g., variable labels, value labels,
print formats, missing values, etc.). The system file
includes not only those variables from the raw data file
but also any variables that subsequently were created
using the COMPUTE or IF commands. The advantage of an
SPSS system file is faster processing time (SPSS doesn't
have to recreate the system file) and less cumbersome
control files for subsequent SPSS runs. Any changes to an
SPSS system file can be saved in an updated SPSS system
file.
An SPSS system file is created on command by the SPSS
program itself, which generates a binary file
designed for specific types of computers using designated
operating systems. This file can be read by any SPSS
program operating on a compatible computer and
operating system. A system file cannot be read by normal
human beings--only by the computer and operating
system for which it was created. That is, a system
file created for a unix computer cannot be read on either
a Windows or a Macintosh computer.
However, there are ways to export a system file
for import on a different type of computer. SPSS
commands permit the renaming, dropping, and
reordering of variables in newly created file. These
task are also accomplished through interface commands.
Some of the more important ones are given below.
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GET FILE
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GET FILE =
[name].sav.
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This command directs the computer to retrieve a
saved system file of the form
[name of the
file].sav
where sav is the extension used for all system
files.
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SAVE
OUTFILE
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SAVE OUTFILE =
[name].sav.
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The SAVE command instructs SPSS to save
the file currently in memory as an SPSS system. The
OUTFILE=output subcommand tells SPSS to name the
system file [name].sav.
The saved file the data and all data definitions and
documention in the file in the computer memory. This
includes any changes you may have made to the file after
retrieving it with GET FILE or after creating the
file from raw data using DATA LIST.
Saving an SPSS system file provides the opportunity to
delete variables from your file and/or reorganize the
sequence in which the variables are saved. Use the
KEEP subcommand to specify the variables you want
to save (and their order) to specify the variables you
want to delete. The command
SAVE
OUTFILE=clinton.sav/KEEP=V1 to v5 REGION POPSIZE
CDBG87 CDBG88.
saves the listed variables in the sequence in which
they are listed in the new system file. Be careful when
using the KEEP subcommand, for any variable not
identified on the list will be deleted from the file.
You also can change variable names on the SAVE command
with the RENAME subcommand. Its syntax is:
SAVE
OUTFILE=bush.sav/RENAME= (old varname=new
varname)
For example
SAVE
OUTFILE=bush.sav/RENAME=
(v1=CITYID) (v2=POP86)(v3=TYPE)
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EXPORT
OUTFILE
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EXPORT OUTFILE =
[name].por.
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EXPORT OUTFILE works just like the SAVE
OUTFILE command, including the KEEP and RENAME
subcommands. The difference is that EXPORT saves a
[name].por file, which is an encoded ASCII
file that can be read by another SPSS program on any
computer.
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IMPORT
FILE
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IMPORT FILE =
[name].por.
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This command functions much like GET FILE,
except that it only accepts [name].por
files saved by the EXPORT command. It then reconverts
[name] to an SPSS file in memory.
After successfully importing a program into SPSS,
almost all users will want to save the SPSS file in
memory as a system file. This can be done with the SAVE
OUTFILE command.
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Once you have saved the [name].por]
file on the unix computer, you must download the
file to your microcomputer. This requires using a File
Transfer Protocol (FTP) program. NU's internet software
disk, "Little Domain on the Prairie," should have loaded
an FTP program on your computer.
If you have you have a Macintosh, look for the program
FETCH. If you have a Windows computer, look for a
Ws_FTP program in the "download" folder. Then use
SPSS for Windows to IMPORT FILE =
[name.por]. Run DISPLAY LABELS to see whether
the process worked.
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