This article was originally published in Perspective, Volume 19, Number 3, 1995, pp. 31-34.
The countdown clock reminds users
to complete the migration off the ES/9000 by June 30, 1996.
by Michael Mitchell, Ph.D.
Would you like to move your MVS SPSS system files to AIX, so you can use SPSS on AIX? Unfortunately, you cannot just copy your MVS SPSS system files to AIX, because SPSS system files can be read only on the platform on which they were created. For example, your SPSS system files created on MVS can only be read on an MVS computer. Fortunately, you can use SPSS to create a "SPSS export file," a kind of generic file which can be transferred to other platforms (such as AIX). The file can then be read on the new platform and used to create an SPSS system file for that platform. This article illustrates how to move an MVS SPSS system file to AIX via an SPSS export file. These instructions may not apply to transfers involving other host systems.
This article describes four steps that you can use to transport an SPSS system file from MVS to AIX. These steps are listed below, and illustrated in Figure 1.
This article provides example setups showing how to move an SPSS system file (called "election.spsssys") from MVS to AIX following these four steps. These sample setups and other associated files are provided online. See the section "For More Information" at the end of this article to learn how to access these online examples.
Figure 2 shows an SPSS job which is written for MVS to convert the SPSS system file AAAAIII.ELECTION.SPSSSYS to an SPSS export file called AAAAIII.SPSSXPT.ELECTION.
The first DD card in the job assigns the ddname INSPSS to the SPSS system file AAAIII.ELECTION.SPSSSYS, and the ddname OUTXPT to the export file to be created, AAAAIII.SPSSXPT.ELECTION. It is important that you create the export file as a fixed block file with a logical record length of 80, and a blocksize of 8000, as shown in the example. To use the file yourself, you only need to change these two DD cards substituting your userid, the name of your SPSS system file, the name of your export file, and the space requirements for your export file.
The program reads the SPSS system file using the GET FILE command. Then, the MVS SPSS system file is inspected using the DISPLAY DICTIONARY, LIST CASES, and DESCRIPTIVES commands. The output created by these commands can be compared to the output generated by inspecting the AIX SPSS system file in step 3. Finally, the EXPORT command is used to write the export file.
SPSS export files can be transported to AIX using FTP. See the companion article in this issue titled "How to Use FTP to Transfer Datasets from MVS to AIX" for information about using FTP to transfer your SPSS export files to AIX. SPSS export files must be transferred using ascii transfer mode.
Figure 3 shows a sample setup written for AIX which converts the SPSS export file "spssxpt.election" to an AIX SPSS system file called "election.sav."
This program illustrates a big difference between using SPSS on AIX and SPSS on MVS. On AIX, input and output commands (like IMPORT, EXPORT, SAVE) can refer directly to the file, without the need for DD cards (or FILE HANDLE commands). The IMPORT command reads the SPSS export file called "spssxpt.election." The SAVE command then saves the contents of the export file into an SPSS system file called "election.sav." Finally, DISPLAY DICTIONARY, LIST CASES, and DESCRIPTIVES commands are used to inspect the AIX SPSS system file.
Steps 1 and 3 included DISPLAY DICTIONARY, LIST CASES, and DESCRIPTIVES commands to inspect the MVS and AIX SPSS system files. These results should be compared to verify that the transfer and conversion were error free.
Examine the output of the DISPLAY DICTIONARY command - Do the MVS and AIX system files have the same variables? Do they have the same missing values? Do they have the same variable labels? Do they have the same value labels?
Examine the output of the DESCRIPTIVES command- Do the variables in the MVS and AIX system files have the same means? Do they have the same number of valid observations?
Examine the output of the LIST CASES command - Do the first ten observations of the MVS and AIX system files contain the same data?
If there is a conflict between the MVS and AIX results, you should repeat the transfer and conversion processes. If the MVS and AIX results still conflict, contact OAC Consulting for assistance (see the section "For More Information" below).
For simplicity, these examples make some assumptions. Step 1 assumes that you are transporting SPSS system files located on disk. Step 3 looks for the SPSS export file in the current directory, and places the SPSS AIX system file in the current directory. It is assumed that the reader knows how to submit batch jobs on MVS and how to submit batch jobs on AIX via LoadLeveler. This article does not describe how to transfer your existing SPSS programs from MVS to AIX. See the companion articles "How to Identify MVS Datasets for Migration" and "How to Use FTP to Transfer Your Datasets from MVS to AIX" for information about how to transfer your SPSS programs to AIX.
Moving SPSS system files with FTP
Example setups for using the SPSS EXPORT command to convert an MVS SPSS system file to an SPSS export file
Example setup for using IMPORT command to convert SPSS export file to AIX SPSS system file
Michael Mitchell, Ph.D., is an OAC Statistical Consultant who provides guidance to users in the implementation of statistical methodologies and the analysis of large and complex databases.
18 Jul 95; Rev. 19 Dec 95