Usability Testing

There are two basic approaches to evaluating and comparing the clarity of alternative user interface approaches – modeling and usability testing. Both approaches are effective for testing new applications and existing. Modeling uses a set of criteria to objectively quantify the characteristics of a hypothetical users experience with the user interface. In cognitive modeling, a set of discrete actions are defined that represent how a user will interact with the interface –viewing a displayed list of options, making a decision, and reaching and pressing the preferred option. Each of these behaviors is assigned a time-based value, for example:

1. Reach and press a button: 1 second
2. Wait for system to update display: .25 seconds
3. Review a list of 5 displayed choices: 5.5 seconds
4. Make a decision among 5 choices: 1.5 seconds
5. Reach, grasp and rotate a knob through 180 degrees: 3 seconds

Note that these particular times are hypothetical values for explanatory purposes. Actual time values would be determined via guidelines and measurements, or even better, by averaging observed user performance with similar systems in cases where you’re interested in usability testing for new applications. Values can vary widely based on the factors such as the user’s level of experience with such an interface, so models need to be appropriately qualified.

With these behavioral times, one can sum the discrete steps a user executes when completing particular tasks within the user interface, and compare the total time across different interfaces. For example, completing a particular task with one version of an interface might require the following sequence of steps: c, d, a (8 seconds); whereas an alternative might require a different set of actions: a, e, b, c, d, a (12.25 seconds). In this case first user interface was less complex, with respect to both task time and numbers steps. *

Continue >>
Contact Bresslergroup directly >>