The Genealogical Proof Standard in Practice
How professional genealogists decide when a conclusion is proven, and how to apply the five elements of the GPS to your own brick walls.
When no single record answers your question, which is most of the time once you're past 1850, you need a way to decide when the evidence is strong enough. The Genealogical Proof Standard (GPS), defined by the Board for Certification of Genealogists, is that framework. It has five elements, and a conclusion is considered proven only when all five are met.
1. Reasonably exhaustive research
Search every source that might hold relevant information, not just the convenient online ones. That usually means probate, deeds, tax lists, court minutes, church records and newspapers for the whole family and its neighbors. "Exhaustive" doesn't mean every record in existence; it means you wouldn't expect any remaining source to overturn your conclusion.
2. Complete and accurate citations
Each fact needs a citation that would let someone else find the same source. Citations also force you to assess quality: is this an original record, a derivative copy, or an index of a transcription of a copy?
3. Thorough analysis and correlation
Assess each piece of evidence on three levels:
- Source: original or derivative?
- Information: primary (from someone with firsthand knowledge), secondary, or undetermined? A death certificate is primary for the date of death but secondary for the date of birth.
- Evidence: direct (it answers the question outright), indirect (it answers only when combined with other evidence), or negative (meaning comes from an absence, such as a man missing from a tax list he should be on)?
Correlation means laying the evidence side by side. Timelines and tables help a lot here. Patterns appear that no single record shows.
4. Resolution of conflicting evidence
When records disagree, you can't just pick the one you like. Explain why one piece of evidence is more reliable: who supplied the information, how close it was to the event, and whether the creator had any reason to be inaccurate.
5. A soundly reasoned, written conclusion
Write it down. A proof can be a single sentence with a citation (if the evidence is direct and uncontested), a proof summary, or a full proof argument for complex cases built on indirect evidence. Writing exposes gaps in reasoning that feel solid in your head.
Further reading
The Board for Certification of Genealogists publishes the standards in full. For citation formats, Evidence Explained by Elizabeth Shown Mills is the standard reference.
Next: Using DNA Matches to Break Through Brick Walls →