Including the file date in the display makes it easy for the user to scan quickly for the most current sites and presumably current information content. Measuring database quality of a database of changeable Internet information resources requires different measures than that for a bibliographic database. In a bibliographic database, the producers can continually strive to eliminate all citation errors and expand the database to cover all relevant citations. Citations to print resources stay static. Internet resources are rarely static.
Sites move, directories are rearranged, and documents are updated.
To maintain a quality database of Web documents, the index needs to be constantly updated and each site needs to be verified on a regular interval. Given that situation, the better quality Web databases will have a more frequent update interval. In addition, the user should find relatively few dead links. Alta Vista seems to score well in both categories. Unfortunately, this feature of the database is not well documented, but based on anecdotal evidence, Alta Vista has fewer dead links and more current updates than some of its competitors.