Skilled Bug Investigation Illustrated - Consider possibility of tester error

In a presentation titled Skilled Testers and Their Enemies, James Bach identifies the steps involved in skilled bug investigation:

The following post is part of a 13-part series illustrating those points using A Study in Scarlet by Arthur Conan Doyle.

Consider possibility of tester error

Holmes is certainly not the poster child for modesty. In fact, in this case he is completely confident of his abilities. It should be noted that in others he is not always so confident. In this tale, the closest I could come to admitting error is the following:

“‘Commonplace,’ said Holmes, though I thought from his expression that he was pleased at my evident surprise and admiration. ‘I said just now that there were no criminals. It appears that I am wrong — look at this!’ He threw me over the note which the commissionaire had brought.”