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:
“When you model yourself on people, you should try to resemble their good sides.”
—Molière [Jean Baptiste Poquelin] (1622–1673)
“Your home is regarded as a model home, your life as a model life. But all this splendor, and you along with it ... it’s just as though it were built upon a shifting quagmire. A moment may come, a word can be spoken, and both you and all this splendor will collapse.”
—Henrik Ibsen (1828–1906)
“...that absolutely everything beloved and cherished of the bourgeoisie, the conservative, the cowardly, and the impotent—the State, family life, secular art and science—was consciously or unconsciously hostile to the religious idea, to the Church, whose innate tendency and permanent aim was the dissolution of all existing worldly orders, and the reconstitution of society after the model of the ideal, the communistic City of God.”
—Thomas Mann (1875–1955)