“Historians employ a number of common-sense principles in assessing the strength of a testimony. Here are five of those principles:
1. Testimony attested to by multiple independent witnesses is usually considered stronger than the testimony of one witness.
2. Affirmation by a neutral or hostile source is usually considered stronger than affirmation from a friendly source, since bias in favor of the person or position is absent.
3. People usually don't make up details regarding a story that would tend to weaken their position.
4. Eyewitness testimony is usually considered stronger than testimony heard from a second- or thirdhand source.
5. An early testimony from very close to the event in question is usually considered more reliable than one received years after the event.”