Model
Fitts's law has been formulated mathematically in several different ways. One common form is the Shannon formulation (proposed by Scott MacKenzie, professor at York University, and named for its resemblance to the Shannon–Hartley theorem) for movement along a single dimension:
where:
- T is the average time taken to complete the movement. (Traditionally, researchers have used the symbol MT for this, to mean movement time.)
- a represents the start/stop time of the device (intercept) and
- b stands for the inherent speed of the device (slope). These constants can be determined experimentally by fitting a straight line to measured data.
- D is the distance from the starting point to the center of the target. (Traditionally, researchers have used the symbol A for this, to mean the amplitude of the movement.)
- W is the width of the target measured along the axis of motion. W can also be thought of as the allowed error tolerance in the final position, since the final point of the motion must fall within ±W⁄2 of the target's center.
From the equation, we see a speed–accuracy trade off associated with pointing, whereby targets that are smaller and/or further away require more time to acquire.
Read more about this topic: Fitts's Law
Famous quotes containing the word model:
“If the man who paints only the tree, or flower, or other surface he sees before him were an artist, the king of artists would be the photographer. It is for the artist to do something beyond this: in portrait painting to put on canvas something more than the face the model wears for that one day; to paint the man, in short, as well as his features.”
—James Mcneill Whistler (1834–1903)
“... if we look around us in social life and note down who are the faithful wives, the most patient and careful mothers, the most exemplary housekeepers, the model sisters, the wisest philanthropists, and the women of the most social influence, we will have to admit that most frequently they are women of cultivated minds, without which even warm hearts and good intentions are but partial influences.”
—Mrs. H. O. Ward (1824–1899)
“When you model yourself on people, you should try to resemble their good sides.”
—Molière [Jean Baptiste Poquelin] (1622–1673)