Prepared by Elisabeth Lindsay.
A derivative source is a record derived from other sources, in other words, it is not an original source a record documenting an event. To say a document is original or derivative refers to the document itself, not the information it contains. Both original and derivative documents can contain either primary information (firsthand) and secondary information (secondhand) -- or both. A death record, for example, is an original source document. An index containing death information is a derivative source (book, database, etc.). A death record may contain primary information, the name of the deceased, the date and time of death; and it may contain secondary information such as birth place and parent's names, if that information is provided by an informant.
Derivative source materials are valuable research tools. For generations genealogical societies, the LDS Church and others have been extracting information from inaccessible documents and making it accessible to the general public. Births, marriage and death indexes; cemetery transcriptions, biographies and local area histories are all examples of derivative source materials. The problem for researchers is the margin of error in derivative source materials through the process of gathering, transcribing and entering data. Materials from such sources can be generally trusted, but when conflict occurs, it becomes important to verify the information across multiple sources, including, if available, the original record. Online family trees and published genealogies are, perhaps, the most suspect of all derivative sources unless well documented, and even then the researcher should verify that all information has transcribed correctly.