GOMS Techniques

In relation to user interface design, GOMS (Goals, Operators, Methods and Selection rules) focuses on the calculation and comparison of different methods of human - computer interaction that serve the same purpose. A GOMS analysis predicts how the user will interact with the proposed system; these predictions assist designers to focus on improving the usability and performance time of human-computer interaction.

Using the following GOMS analysis figures to calculate one human - computer interaction against another, a designer is able to successfully design and simplify a system that requires the least amount of time possible to complete a certain task.

K:	0.28 sec	Pressing a key
T(n):	n x K	Typing a sequence of n characters
P:	1.1 sec	Pointing with a mouse
B:	0.1 sec	Pressing OR releasing a mouse button
H:	0.4 sec	Moving the hand between the keyboard and mouse
M:	1.2 sec	Mental act of routine thinking or perceiving

Using a combination of the above, for example:

Login to a computer would involve:

- typing in your username (roger)
- tabbing to the password field
- typing in your password (testing)
- moving your hand from the keyboard to the mouse
- pointing the mouse
- pressing the mouse

which would equal

= T(n) + K + T(n) + H + P + B
= (0.28 x 5) + 0.28 + (0.28 x 7) + 0.4 + 1.1 + 0.1
= 5.24 seconds