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The Genealogical Proof Standard

Applications for certification are judged on whether they meet the standards delineated in Genealogy Standards. All of its eighty-three standards contribute to the level of credibility in genealogy called the Genealogical Proof Standard (GPS). As a result, genealogists who are certified have demonstrated their ability to do work that meets the GPS.

Proof is a fundamental concept in genealogy. In order to merit confidence, each conclusion about an ancestor must have sufficient credibility to be accepted as "proved." Acceptable conclusions, therefore, meet the Genealogical Proof Standard (GPS). The GPS consists of five elements:

  • reasonably exhaustive research;
  • complete, accurate citations to the source or sources of each information item;
  • tests—through processes of analysis and correlation—of all sources, information items, and evidence;
  • resolution of conflicts among evidence items; and
  • a soundly reasoned, coherently written conclusion.

Each element contributes to a conclusion's credibility in a different way, described in the table below, but all the elements are necessary to establish proof.

Element of the GPS
Contribution to Credibility
Reasonably exhaustive research
  • Assumes examination of a wide range of high quality sources
  • Minimizes the probability that undiscovered evidence will overturn a too-hasty conclusion
Complete, accurate citations to the source or sources of each information item
  • Demonstrates the extent of the search and the quality of the sources
  • Allows others to replicate the steps taken to reach the conclusion. (Inability to replicate the research casts doubt on the conclusion.)
Tests—through processes of analysis and correlation—of all sources, information items, and evidence
  • Facilitates sound interpretation of the data contributed by each source
  • Ensures that the conclusion reflects all the evidence 
Resolution of conflicts among evidence items
  • Substantiates the conclusion's credibility. (If conflicting evidence is not resolved, a credible conclusion is not possible.)
Soundly reasoned, coherently written conclusion.
  • Eliminates the possibility that the conclusion is based on bias, preconception, or inadequate appreciation of the evidence
  • Explains how the evidence led to the conclusion 


Applicants for research-category certification are required to demonstrate they fully understand the GPS and can apply it to research situations. The parts of an application that specifically test this knowledge include the case study and kinship-determination project.

The GPS reflects a change from the term "Preponderance of the Evidence," used earlier to describe the high standard of proof BCG had always promoted. (For further information about this topic, click here for information on BCG's decision and here for a detailed article on this subject.) Case studies in national genealogical journals, such as the National Genealogical Society Quarterly and The American Genealogist, illustrate the GPS.




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