Breadth versus Depth

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One issue regarding menu design is known as the breadth versus depth trade-off. One alternative is to have only a few choices on every menu page and many, or at least more, levels in the menu hierarchy. This deep hierarchy results in many cascading menus. The other alternative would be to have more options on an individual menu page, thereby reducing the number of levels in the hierarchy, and increasing the breadth.

The question is which alternative is best? Research has shown that it is usually better to minimize depth at the expense of breadth. This means avoiding the use of cascading menus at the expense of long menu pages.

The optimum length of a menu page depends on three variables:

•User experience and frequency of use.

•Extent to which menu options can be grouped

•Extent to which choices are complex and require categorical judgment.

The following table shows the relation between these three variables and the optimum length of a menu page.

Relation between User/Task Variables and Optimum Number of Options

User task Variables

Optimum Number of Menu Options

Options are complex, and/or options CANNOT be grouped

Up to 10 options per menu page

Options are NOT complex, and options CAN be grouped, but users are infrequent or casual users

11 to 20 options per menu page

Options are NOT complex, and options CAN be grouped, and users are frequent/expert users

21 or more options per menu page

Use this table to determine the maximum optimal length of the menu pages in your application. Then use this length, as a starting point to determine how much depth is necessary to include all your menu options. In addition:

•Put frequently used options high in the hierarchy.

•Order menu options according to one or more of the following principles:

oConvention

oFrequency of use

oOrder of use

oCategorical or functional groups

oAlphabetical order

•The first option on the menu page should not be the most important (because it is relatively difficult to activate with the mouse).

NOTE: Each user group has its own menu structure. The maximum number of menu options per user group menu must not exceed 999. If you define more options, you may encounter unexpected system behavior.

The hierarchical menu system consists of menu pages that have a title plus a list of options (menu lines). Each menu option is a combination of:

•A line of text (i.e. the text that appears on the menu).

•Some kind of action (e.g. activate a window, a batch job, a method call, or a submenu).

•A specification of whether or not the menu option must be sensitive to the state the system is in.

The possibility of having a menu page contain other menu pages gives the menu system its hierarchical structure.