Do Filters Block 21 Percent? Perhaps, But Probably Not at Libraries
Staff -- Library Journal, 2/7/2000
"Filters block an average of 21 percent -- or one out of every five sites containing legal, useful information," declares the American Library Association's Libraries & the Internet Toolkit, which was distributed at the Midwinter Meeting in San Antonio. The source for that statement was a 1999 thesis on filtering by University of Pennsylvania graduate student Christopher Hunter. His test of four popular filtering products -- Net Nanny, CYBERSitter, CyberPatrol, and SurfWatch -- declared that, on average, filters "will overinclusively block 'innocuous' material 21 percent of the time" and "fail to block 'objectionable' material 25 percent of the time." However, filters used by libraries probably overblock at lesser percentages; Hunter performed his test with default settings on, meaning all blocking categories were enabled, while many libraries using filters attempt to winnow the categories. Hunter points out that two products -- CYBERSitter and Cyber Patrol -- are overinclusive, blocking a larger percentage of targeted material but also many legitimate sites, while SurfWatch and Net Nanny err in the other direction, blocking fewer innocuous sites but allowing "a tremendous amount of objectionable material."
