Edelman then assembled a database of Web sites for possible testing.  He derived this list by automatically compiling URLs from the Yahoo index of Web sites, taking them from categories from the Yahoo index that differed significantly from the classifications that he had enabled in each of the blocking programs (taking, for example, Web sites from Yahoo’s “Government” category).  He then expanded this list by entering URLs taken from the Yahoo index into the Google search engine’s “related” search function, which provides the user with a list of similar sites.  Edelman also included and excluded specific Web sites at the request of the plaintiffs’ counsel.

Taking the list of more than 500,000 URLs that he had compiled, Edelman used an automated system that he had developed to test whether particular URLs were blocked by each of the four filtering programs.  This testing took place between February and October 2001.  He recorded the specific dates on which particular sites were blocked by particular programs, and, using commercial archiving software, archived the contents of the home page of the blocked Web sites (and in some instances the pages linked to from the home page) as it existed when it was blocked.  Through this process, Edelman, whose testimony we credit, compiled a list of 6,777 URLs that were blocked by one or more of the four programs.  Because these sites were chosen from categories from the Yahoo directory that were unrelated to the filtering categories that were enabled during the test (i.e., “Government” vs.  “Nudity"), he reasoned that they were likely erroneously blocked.  As explained in the margin, Edelman repeated his testing and discovered that Cyber Patrol had unblocked most of the pages on the list of 6,777 after he had published the list on his Web site.  His records indicate that an employee of SurfControl (the company that produces Cyber Patrol software) accessed his site and presumably checked out the URLs on the list, thus confirming Edelman’s judgment that the majority of URLs on the list were erroneously blocked.  Edelman forwarded the list of blocked sites to Dr. Joseph Janes, an Assistant Professor in the Information School of the University of Washington who also testified at trial as an expert witness.  Janes reviewed the sites that Edelman compiled to determine whether they are consistent with library collection development, i.e., whether they are sites to which a reference librarian would, consistent with professional standards, direct a patron as a source of information.

Edelman forwarded Janes a list of 6,775 Web sites, almost the entire list of blocked sites that he collected, from which Janes took a random sample of 859 using the SPSS statistical software package.  Janes indicated that he chose a sample size of 859 because it would yield a 95% confidence interval of plus or minus 2.5%.  Janes recruited a group of 16 reviewers, most of whom were current or former students at the