2005-11-04 On 2005-03-14 new files were added to one
or more datasets. These files included additional setup files as well
as one or more of the following: SAS program, SAS transport, SPSS portable,
and Stata system files. The metadata record was revised 2005-11-04 to
reflect these additions.
1999-02-17 Each of the three data files has been completely
reprocessed to logical record length format. Also, the codebooks for
each file have been combined into a single PDF codebook covering all
parts. The SPSS data definition statements have been updated to
reflect the changes, and SAS data definition statements have been
1986-06-06 ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:
- Standardized missing values.
2006-03-30 File CB8417.ALL.PDF was removed from any previous datasets and flagged as a study-level file, so that it will accompany all downloads.