Method for measuring the usability of a system
First Claim
1. A method for operating a computer to provide a quantitative usability measure for evaluating usability of a system, said system including a process, product, or manufacturing procedure and having means for performing a task, said task including at least one step, said method comprising the computer executed steps of:
- measuring first time value signals for each member of an Expert population to perform said task on each of a plurality of trials;
measuring second time value signals for each member of a Novice population to perform said task on each of at least one trial;
estimating, according to a predetermined relationship, a mean time for said Novice population to perform said task on a future trial;
comparing a mean time for said Expert population to perform said task on a trial equivalent in number of trials to said future trial with said mean time for said Novice population to generate a statistical index indicating a significance of the difference therebetween; and
providing said quantitative usability measure as a function of said statistical index.
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Abstract
A method for quantitatively and objectively measuring the usability of a system. The method provides quantitative measures for usability satisfaction, usability performance, and usability performance indicators. Usability satisfaction is measured by acquiring data from a system user population with respect to a set of critical factors that are identified for the system. Usability performance is measured by acquiring data for quantifying the statistical significance of the difference in the mean time for an Expert population to perform a task on a particular number of trials and the estimated mean time for a Novice population to perform the task on the same number of trials. The estimated mean time is calculated according to the Power Law of Practice. Usability Performance Indicators include Goal Achievement Indicators, Work Rate Usability Indicators, and Operability Indicators which are calculated according to one or more measurable parameters which include performance times, numbers of problems encountered, number of actions taken, time apportioned to problems, learning time, number of calls for assistance, and the number of unsolved problems.
122 Citations
18 Claims
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1. A method for operating a computer to provide a quantitative usability measure for evaluating usability of a system, said system including a process, product, or manufacturing procedure and having means for performing a task, said task including at least one step, said method comprising the computer executed steps of:
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measuring first time value signals for each member of an Expert population to perform said task on each of a plurality of trials; measuring second time value signals for each member of a Novice population to perform said task on each of at least one trial; estimating, according to a predetermined relationship, a mean time for said Novice population to perform said task on a future trial; comparing a mean time for said Expert population to perform said task on a trial equivalent in number of trials to said future trial with said mean time for said Novice population to generate a statistical index indicating a significance of the difference therebetween; and providing said quantitative usability measure as a function of said statistical index. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for operating a computer to provide a quantitative usability measure for quantitatively evaluating usability of a system, comprising the computer executed steps of:
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acquiring first data for providing a usability satisfaction measure according to a set of critical factors of said system; measuring second data for providing a usability performance measure according to the difference between a measured performance time for an Expert population to perform a task on a given trial and an estimated performance time for a Novice population to perform the task on the given trial; measuring third data for providing a Usability Performance Indicator; and processing said first, second, and third data to provide quantitative values for said usability satisfaction, said usability performance, and said Usability Performance Indicator.
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Specification