Two patterns must be separated: consistently inadequate retention and a deterioration occurring later in life.
First pattern: the narrator was not generally precise, and errors are not confined to a particular later event.
Second pattern: the narrator was formerly accurate but subsequently experienced serious confusion following age-related decline, illness, loss of sight, or the loss of a dependable book collection.
In the second situation, treating all transmissions across a lifetime identically can be misleading. It is crucial to determine whether a student heard the narrator before or after the deterioration. The date of transmission can directly affect the report’s assessment.