Guidelines for menu hierarchies

• Submenus of the currently touched menu item should be automatically shown (30% less search time and 50% less errors for beginning users, Snowberry et al., 1985).
• Menus should not be deeply nested (2-3 levels only).
• The menu lenght should not exceed 3-12 items. Menus may be longer if they are grouped or if items have a natural sequence.
• On the top level and particularly on the bottom ("leaf") level, menus should be longer than in the middle of the hierarchy (Norman & Chin, 1988).
• Longer menus are better when working under time pressure (Wallace, 1988)
• The total number of different menus in a hierarchy should be low (Norman 1991). If possible, combine two or more intermediate menus into a single one and deactivate those menu items that do not occur in the respective navigation path.
• All entries of the same level should fit on a screen (no scrolling should be necessary).
• The hierarchy should be constructed thematically. Sometimes menu hierarchies can be constructed based on which items are frequently selected together.
• Constructing hierarchies top-down or bottom-up? (Chin, 1986):
• Top-down approach yields broader trees (more menu entries on the top level) and deeper trees. The emphasis lies on the discrimination of the differences between items.
• Bottom-up approach yields narrower trees with broad lowermost level. The emphasis lies on the clustering of related items.
  * Use a combined approach.
• Consider menu shortcuts to deeper hierarchy levels.
• External consistency (with previous program versions or competitive programs): changing the hierarchical position of menu entries is o.k., as long as lexical identity is preserved (Foltz et al., 1988).