The “Three Plumbers” Rule

All I need is one good plumber, not three mediocre ones.

According to some in the land of genealogy, if I have three sources that say the same thing, then I have “proof.”

No. You have three sources that say the same thing and there’s a little more to information analysis than reaching some magic number.

One has to consider how “independent” the sources really are. Is the same person the informant on all three sources and providing the same information? If so that’s not three independent sources. It’s really one informant. The same thing applies if two published genealogies copy a statement from the same reference. That is a case of one source–not three.

And also: how reliable are those sources? Did the informant know what they were talking about? Who was the informant?

One reliable source is better than three sources that are not. The difficulty rests in determining how independent and reliable individual sources are.

Three unreliable plumbers will not fix my problem. I have a much better chance with one who knows what they are doing.

Too many bad sources in your research and you’ll have a stopped-up genealogical sink.

Add Genealogy Tip of the Day–the book–to your bookshelf!

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