Critics noted that the target date had been changed a number of times from late in 2006 to early in 2009. It was also criticized on grounds that a count is impossible because "word" is not a scientifically valid concept. Google addressed this situation by counting the words in the 15 million scanned texts in their corpus. Global Language Monitor states the general criteria for inclusion on its site, maintaining that it is simply updating the established criteria for printed dictionaries beginning with the works of Samuel Johnson and Noah Webster.