Determining If a Source is Relevant
After finding a potential source, figure out if it is actually about your ancestor. If it is relevant you can add to what you know about that ancestor. This often provides clues for further research. It will certainly help better identify the ancestor. If a source is not relevant, tell why in order to help other researchers.
Compare old and new information. Correlate all information about the ancestor and compare it with information from the new source.
Look for unique identifiers. Look for at least two or three unique data or identifiers shared by both the new source, and what you already know.
Relatives as identifiers. The relatives and friends in close proximity are among the most unique and best identifiers. For example, if a person named Fox married someone named Pace, those two surnames appearing together in records as married would usually be so unique you could be confident you had identified the same couple. Likewise, parents, siblings, children, and sometimes neighbors appearing together can be convincing evidence a new source is about the correct ancestor. Unique similar names, or a group of names in close proximity, unique similar dates, unique similar places, and unique similar sources can all be used as identifiers to help judge whether a new found source is likely to be about a given ancestor.
Specific data are best. The more specific the data are, the better.
Vague or incomplete data. Be especially cautious when the only matching information is vague or incomplete. A common name, or a year-only date, or a state-only (and sometimes county-only) identifier may not be unique enough.
Compare the number of matching with mismatching identifiers. The more unique identifiers that match, and the fewer that mismatch, the more sure you can be a new source is relevant.
Does it fit the pattern? Also, analyze whether events in the new source fit the pattern of your ancestor. Is it likely that the event described could have happened as described to your ancestor?
When in doubt, tentatively guess a new source is not relevant (or hold it in abeyance).
Minor discrepancies do not prevent a match, and are to be expected. But it is a genealogist's responsibility to acknowledge and explain discrepancies and contradictory evidence.
Preliminary follow up. Once you decide to accept a new source a relevant or not, explain your decision on your research log. If the source seems possibly relevant, photocopy the document, and add the new information from the new source as new event(s) on the ancestor's family group record. Be sure to add a source citation footnote for each event. In the footnote add a short preliminary evaluation of the source. File the source photocopy and updated family group record in their correct places.
Later final analysis. Later, after you have thoroughly researched all the family members of the ancestor, it is important to reconsider your preliminary acceptance of a source as relevant. When almost all that can be gathered about the family is assembled, correlated, corroborated, and analyzed in its totality, you are in a better position to make a final judgment about the relevance of an individual source.