A teaching tool for researchers just came across EE's desk. To paraphrase: The tool asks whether a needed record exists. Then it instructs: If it does not exist, you now have negative evidence.
No. Nope. Non and nyet!
Oh, joy! Testing Company XYZ has just posted a new match for me! It confirms just what I thought! He and I both descend from Will Whoozit and his wife Alice!
Hmhh. Confirms? How?