Selection time for menu items

The time necessary to select an item i from a menu of length n is composed of the search time S plus

in the case of selection via a keyboard code: the time necessary to press the key(s);
in the case of selection with a pointing time: the positioning time P, plus the activation time (e.g. the mouse click).

Search time S

1.1 Beginning users

There are three possible search strategies

(1) Serial inspection

(2) Random inspection without repeat (implausible)

(3) Random inspection with repeat

In all three cases, S is proportional to n. In case (3), both the expected means and the variance is higher than in (2) and (1).

1.2 Advanced users

Advanced users remember the approximate position of frequently used items fairly well. The search time S then is nearly constant (i.e., independent of n).

Finger pointing to the right The length of a menu influences the search time only when the user is a beginner.

Finger pointing to the right The search time of beginners is likely to be shorter if frequently-used items are placed on top.