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Accessing a Data Set on American States
Up to now, you have only used SPSS to create your own small SPSS file.
  • The first SPSS run created your ten cases.
  • The second run used the "data management" capability of SPSS to add two new variables.
  • The third run asked you to use the "compute" procedure in SPSS to compute VOTEGAIN--the number of electoral votes each state gained between the 1990 and 2000 censuses.
  • In these runs, you used only a small number of cases and a few variables.
  • Through the rest of the course, you will be using full data sets created by others and stored as SPSS "system files."

SPSS system files combine raw data and data definition cards, so that the data do not need to be entered anew each time, and the variables can be referred to directly by the 8-character names assigned to them.

  • SPSS system files are designated as the "filetype" *.sav. [where * = the name of the file]
  • All SPSS system files (and thus all *.sav files) are "binary" files, which means that they are stored in computer code that cannot be read by people from this planet.
  • However, these SPSS system files can be processed very efficiently by SPSS.

SPSS can also generate portable files that are encoded into ASCII form and translatable, in turn, into system files.

  • These files can sent via e-mail (if they are small enough).
  • I have created a "portable" file called "states2000.por" that I will be sending you via e-mail.
  • After you open states2000,por, save it as states2000.sav.
  • Then you have your own SPSS system file.

SPSS can also open Excel spreadsheet files, which have the extension .xls.

  • I prepared an Excel file containing data on voting turnout in the 2000 presidential election.
  • voting2000.xls was sent as an e-mail attachment.
  • You were asked to open that file and to save it as voting2000.sav.

For Friday, I'm asking you to add the voting turnout data to the states data, using the SPSS Merge Files command. Here's what you do:

  1. Launch SPSS and access states2000.sav
  2. Pull down DATA from the Menu bar.
  3. Move down to Merge Files and choose Add Variables.
  1. You'll get a box asking you to choose the "Read File" (the file from which you are to read variables into "states2000." Open "voting2000" (presumably in .sav format).
  1. You'll get another box with a list of variables in the "new working file."
  1. If you scroll down, you'll see that the "voting2000" variables are at the very end.
  2. Click on OK and the new variables will be added at the very end of the file.
  3. Save "states2000" and the voting turnout data will be added to your existing file.

That's it for Friday.