Q.What is secondary data? State its main published and unpublished sources, and the precautions to be taken before using it.

Secondary data already exists, so the answer covers where to find it and how to check it before use.

Secondary data is data that has already been collected by someone else for an earlier purpose and is now re-used by the present investigator.

Published sources (printed and publicly available):

• Official government publications — statistical agency reports, the census, departmental reports (agriculture, industry, labour, finance).
• Semi-official and international publications — central-bank and international-agency reports.
• Reports of committees and commissions appointed to enquire into specific problems.
• Publications of trade associations, chambers of commerce, research institutions and universities.
• Journals, newspapers and periodicals carrying regular economic and business data.

Unpublished sources (held in records, not printed for the public):

• The internal records and files of businesses and offices — sales, purchase, cost, personnel records.
• Records of government departments and research workers not released as publications.

Precautions before use — because it was collected for another purpose, secondary data must be scrutinised for its:

1. Suitability — does it match the present enquiry's definitions, units, coverage and period?
2. Reliability — who collected it, by what method and with what accuracy? Is the source dependable and unbiased? …

A frequent omission is the precautions — many students list only the sources and forget that secondary data must be checked for suitability, reliabi …