Method for measuring the usability of a system and for task analysis and re-engineering
First Claim
1. A method for task analysis and re-engineering of a system, said system including means for performing a task, said task including at least one step, said method comprising the steps of:
- measuring usability of said system to provide quantitative measurements of said task for a population of users, wherein the quantitative measurements include a time characteristic that is computed by converting time segments into a digital performance time, and a satisfaction characteristic of the users;
determining a population statistical index for a set of said population according to values based on said quantitative measurements, wherein the population statistical indexes are based on the variance between said quantitative measurements;
determining a comparable statistical index for each of a plurality of subsets of said set of said population;
processing said comparable statistical index for the plurality of subsets to identify a feature for re-engineering.
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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. A task analysis and re-engineering methodology statistically compares quantitative usability measurements according to various classified subsets of the overall population. Such subsets or categories include population, critical factors, a critical factor, vital critical factors, other demographic groups, etc. Preferably, such subsets are set forth in a hierarchical manner such that the statistical comparison identifies a root task characteristic for re-engineering. Task analysis and re-engineering may also be performed according to activity on arrows, and activity in nodes techniques.
165 Citations
19 Claims
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1. A method for task analysis and re-engineering of a system, said system including means for performing a task, said task including at least one step, said method comprising the steps of:
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measuring usability of said system to provide quantitative measurements of said task for a population of users, wherein the quantitative measurements include a time characteristic that is computed by converting time segments into a digital performance time, and a satisfaction characteristic of the users; determining a population statistical index for a set of said population according to values based on said quantitative measurements, wherein the population statistical indexes are based on the variance between said quantitative measurements; determining a comparable statistical index for each of a plurality of subsets of said set of said population; processing said comparable statistical index for the plurality of subsets to identify a feature for re-engineering. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for task analysis and re-engineering of a system, said system including means for performing a task, said task including at least one step, said method comprising the steps of:
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identifying activities of the task and characteristics of each of the identified activities, the characteristics including time, sequences, and interdependencies, wherein the time characteristic is computed by converting time segments into a digital performance time value; computing an average performance time value for each of a plurality of novice users performing the task for one of a plurality of trials; computing an average performance time value for each of a plurality of expert users performing the task for one of a plurality of trials by using a different task analysis technique; comparing the average performance time value of novice users with the average performance time value of expert users to compute a system average performance time value; and outputting a measure of the system average usability performance value indicating the confidence level of novice and expert users acceptance. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification