daXXXX (where 'da' means 'Data')sdesXXXX (where 'sdes' means 'Study Description')cbXXXX (where 'cb' means 'code-book')ddXXXX (where 'dd' means 'data definition')quXXXX (where 'qu' means 'Questionnaires')spXXXX (where 'sp' means 'SPSS program')saXXXX (where 'sa' means 'SAS program')XXXX' in these examples stands for the 4-digit study number.
Any of these files which exist in the listing can be viewed on
the RCF or downloaded from the ITS datastor Web page.
Once downloaded, sdes, cb, and dd files
can be used as guides to the data.NOTE that some studies may have different naming schemes than described above, but will still have data and (usually) Code Book files in their directories. In such cases, look for "readme" or other explanatory files that might be helpful. If no description or code-book files exist in the directory for this study, users must contact ICPSR in Michigan (see below) for further information.
Compressed files.
Note that many ICPSR files are compressed, usually by means of
the gzip method, though not all have the usual
.gz extension.
If a downloaded file seems to contain "garbage" you might
assume that it is compressed, and follow these steps to uncompress
the file. (The example assumes a file called xx0000.a
as the downloaded "garbage" file.)
- cp xx0000.a xx0000-a.gz
- gunzip xx0000-a.gz
You will then have the files xx0000.a and
xx0000-a.
Once you verify that the gunzipped file (xx0000-a)
is usable (i.e., has been uncompressed successfully), you can
then delete the original file (xx0000.a) and proceed.
NOTE that some files originally compressed at the ICPSR site, and noted in ICPSR descriptions as compressed, may have been uncompressed prior to being stored here at USC, in which case you can usually use the files immediately without further processing.