[Please excuse cross-posting.] I have been doing some additional research on error correction, particularly as it might apply to Project Gutenberg eBooks, but also in more general terms. In my previous thoughts on this subject I came to the conclusions that perhaps 1/2 of the errors present would/could/should be found via each additional proofreading pass, provided it was done by an external source to the previous proofreadings. [Proofreaders do tend to miss the same errors more often the second time around.] However, my most recent research, in conjunctions with the head of error correction at a major publisher, leads me to think 1/3 of errors might be found per pass, instead of the previous 1/2. If any of you have any suggestions as to what these figures are, please let me know. Thanks So Much!!! Michael S. Hart Project Gutenberg