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Creating “Usable” Data from the Recovered Data

Converting the Data

  • For technical reasons, the data were typically downloaded from the Unisys in two forms, assuming the data were all in:
    • Excess-3 character set
    • FIELDATA character set
  • If the character set of the underlying data is known, recovered files can be converted to usable formats (e.g., ASCII) through known mappings

Challenges

  • Data in a record might employ multiple character sets
  • Record layout explaining variables, their lengths, and character set employed may no longer exist or may be incorrect
    • A file showing the first 100 records using 5 different character set assumptions created when the data were downloaded can help reveal variable length and character set
    • Existing microdata and/or published data can help in determining variable content
  • Data files may have other problems such as missing variables or observations, corrupted data, not matching the description in the paper records, etc.

 Interested in these  Recovered Data?

Email the Recovered Data Team to learn more.


Punch Card Entry of 1935 Business Census

Recovery of Historical U.S. Census Bureau Microdata: Success to Date
PDF (3.5 MB)
(Excerpt from 2009 CES Annual Report)


 What are Census  Research Data Centers?

Census Research Data Centers (RDCs) are U.S. Census Bureau facilities, staffed by a Census Bureau employee, which meet all physical and computer security requirements for access to restricted–use data. At RDCs, qualified researchers with approved projects receive restricted access to selected non–public Census Bureau data files.


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Source: U.S. Census Bureau | Center for Economic Studies | (301) 763-6460 | E-mail CES |  Last Revised: October 23, 2012