The deep web in institutional repositories in Japan



Investigating the current status of the deep web is important for both the general public and researchers. Several deep web surveys have recently been conducted on institutional repositories (IRs). We calculate the extent of the deep web based on the content of searchable IRs in Japan, but using a more appropriate interval and exhaustive search with three major search engines (Google, Yahoo!, and Bing). The deep web is roughly 30% of major search engines' coverage.