File Name: usability meanings and interpretations in iso standards .zip
The usability of a software product has recently become a key software quality factor. The International Organization for Standardization ISO has developed a variety of models to specify and measure software usability but these individual models do not support all usability aspects.
- ISO 9241: Introduction
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- Usability meanings and interpretations in ISO standards
Founded on 23 February , the organization promotes worldwide proprietary, industrial, and commercial standards.
In the dusty institutions where usability standards gather to party with each other, ISO is a bit of a celebrity. It is widely cited by people who would be hard pushed to name any other standard, and parts of it are virtually enshrined in law in some European countries such as the UK. Ah, VDTs: as evocative of the eighties as yuppies and punk rock music. It is a shame that ISO is more widely cited than read because it includes a wealth of information that covers every aspect of usability, including hardware, software and usability processes. You could use the standard to design a workstation, evaluate a display, set usability metrics, evaluate a graphical user interface, test out a new keyboard, assess a novel interaction device such as a joystick, check that the working environment is up to scratch, and measure reflections and colour on a display screen.
ISO 9241: Introduction
And if there were one, what would it measure? Unlike temperature, usability is not a property of a person or thing. To properly measure and manage the usability of interfaces, we need to first agree on a definition of usability. In this article, we cover where ISO Part 11 came from and where it seems to be going. The term usability existed well before the s ; for example, it appeared as a key feature in a refrigerator advertisement in the Palm Beach Post on March 8, The modern industrial use of the term started in the late s.
Related terms from that time were user friendliness and ease of use , both of which usability has since displaced in professional and technical writing on the topic.
There are two major conceptions of usability : measurement-based goals summative evaluation versus detection and elimination of problems formative or diagnostic evaluations. Where did the defining begin? Starting in the early s, the goal of the European MUSiC project was to develop specific usability measurement methods for the high-level constructs of effectiveness , efficiency , and satisfaction.
Attempts to measure these constructs did not start with MUSiC. Systematic collection of task completion rates , task completion times , and sometimes satisfaction had been common in industrial usability testing since the early s. IBM conducted an internal competitive usability testing project named SUMS System Usability MetricS in the late s that collected usability benchmarks of success rates, completion times, and satisfaction for three office software suites, with the SUMS data used to develop one of the first standardized usability questionnaires, the PSSUQ.
The MUSiC project was, however, one of the first, if not the first, comprehensive public investigations into the systematic collection of what we now think of as prototypical usability metrics. This empirical work was conducted to support the development of ISO , which had its first draft in One of the early work efforts in the MUSiC project Rengger, was the production of a list of potential usability measurements.
The list was based on 87 papers that had described some quantification of usability, with the measures categorized into four classes:.
These objective usability metrics are familiar to most modern usability and UX practitioners, but note the absence of any subjective metrics.
Using this as a starting point, the MUSiC usability measures proposed in included. From these fundamental measures, additional measures were derived, such as learnability changes in usability over time, or comparisons of experienced and inexperienced users and breakdowns of task time into productive and unproductive periods.
The measures of overall usability continued to be effectiveness, efficiency, and satisfaction, with the following examples:. The standard also included a list of modifications of these key measures for special situations, including:. The standard included workload as a subcategory of efficiency measurement but did not make any specific recommendations. The list of recommended standardized questionnaires continued to include the SUMI but was expanded to include the PSSUQ and QUIS—notably absent was any recommendation for what was the most widely used questionnaire, the SUS , although that might be due to its relatively late publication in After remaining unrevised for two decades, ISO was withdrawn and replaced with ISO , thirty years after its first draft.
Bevan et al. Other key changes included. The most surprising change in the revised draft was that it no longer provided specific guidance on how to measure usability.
In , Nigel Bevan , a central figure in the development of ISO usability standards, wrote an essay for the Journal of Usability Studies that provided some insight on the changes that were to come. As mentioned above, Nigel Bevan was an important leader in the development of the ISO usability standards, working on them for almost four decades before his untimely death in In , a special issue of the Journal of Usability Studies was dedicated to him.
We encourage you to read about his remarkable life and career. The original definition of usability was embodied in ISO Part 11 as a combination of effectiveness, efficiency, and satisfaction. The ISO standard was heavily influenced by the European MUSiC project, which was a publicly funded investigation into the systematic collection of summative usability data, both objective and subjective.
But what exactly does it mean to someone whose job is to improve usability? Through the s and s, the field struggled to find a definition. Early History of Usability The term usability existed well before the s ; for example, it appeared as a key feature in a refrigerator advertisement in the Palm Beach Post on March 8, The list was based on 87 papers that had described some quantification of usability, with the measures categorized into four classes: Class 1 : Goal achievement indicators such as success rate and accuracy Class 2 : Work rate indicators such as speed and efficiency Class 3 : Operability indicators such as error rate and function usage Class 4 : Knowledge acquisition indicators such as learnability and learning rate These objective usability metrics are familiar to most modern usability and UX practitioners, but note the absence of any subjective metrics.
Using this as a starting point, the MUSiC usability measures proposed in included Effectiveness : Measures related to the accuracy and completeness with which task goals are achieved.
For example, if the task is to transcribe a document into a specified format, effectiveness measures would include transcription accuracy, number of deviations from the specified format, and completeness of the transcription. Efficiency : Measures related to the expenditure of mental or physical resources.
Task time is one such measure, as are those that combine task time or another measure of effort with effectiveness. Satisfaction : Measures of perceived usability and acceptability, including direct measures from the SUMI standardized usability questionnaire or indirect measures derived from ratios of positive and negative user comments.
The measures of overall usability continued to be effectiveness, efficiency, and satisfaction, with the following examples: Effectiveness : Percentage of goals achieved; percentage of users completing a task; average accuracy of completed tasks Efficiency : Time to complete a task; tasks completed per unit time; monetary costs of performing the task Satisfaction : Rating scale for satisfaction; frequency of discretionary use; frequency of complaints The standard also included a list of modifications of these key measures for special situations, including: Meet needs of trained users Meet needs to walk up and use Meet needs for infrequent or intermittent use Minimization of support requirements Learnability Error tolerance Legibility The standard included workload as a subcategory of efficiency measurement but did not make any specific recommendations.
Other key changes included Consideration of a wider range of goals, including personal and organizational outcomes. Addition of potential negative consequences of use e. Clarification of satisfaction to include a wider range of issues.
Note on Nigel Bevan As mentioned above, Nigel Bevan was an important leader in the development of the ISO usability standards, working on them for almost four decades before his untimely death in Sign-up to receive weekly updates.
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And if there were one, what would it measure? Unlike temperature, usability is not a property of a person or thing. To properly measure and manage the usability of interfaces, we need to first agree on a definition of usability. In this article, we cover where ISO Part 11 came from and where it seems to be going. The term usability existed well before the s ; for example, it appeared as a key feature in a refrigerator advertisement in the Palm Beach Post on March 8, The modern industrial use of the term started in the late s. Related terms from that time were user friendliness and ease of use , both of which usability has since displaced in professional and technical writing on the topic.
Usability meanings and interpretations in ISO standards
Despite the authoritative nature of international standards for usability, many of them are not widely used. This paper explains both the benefits and some of the potential problems in using usability standards in areas including user interface design, usability assurance, software quality, and usability process improvement. Over the last 20 years, industry and academic experts in human-computer interaction HCI , ergonomics, and usability have met to put together a wide range of authoritative prerequisites and guidelines for designing, developing, and evaluating usable products.
Before ISO there was MUSiC
This paper presents an empirical study based on a set of measures to evaluate the usability of mobile applications running on different mobile operating systems, including Android, iOS and Symbian. The aim is to evaluate empirically a framework that we have developed on the use of the Software Quality Standard ISO in mobile environments, especially the usability characteristic. To do that, 32 users had participated in the experiment and we have used ISO and ISO standards for objective measures by working with two widely used mobile applications: Google Apps and Google Maps. The QUIS 7. By analyzing the results we highlighted a set of mobile usability issues that are related to the hardware as well as to the software and that need to be taken into account by designers and developers in order to improve the usability of mobile applications. Furthermore, in nearly billion of mobile applications were downloaded, versus 64 billion in In , it is expected that this number will increase to billion download Gartner
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