To overcome shortcomings in these studies, the National Institute for Occupational Safety and Health (NIOSH) has proposed two case-control studies that will address the effectiveness of EDs in reducing the robbery rate in Virginia convenience stores, and their effectiveness in reducing robbery-related injuries in stores in major metropolitan areas in nine States. EDs that will be considered in these studies include cash handling procedures, security systems, store layout, visibility, concealed access and escape, location and traffic potential, and staffing characteristics. 2 tables and 18 references