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This article discusses the importance of following design guidelines and using metrics to evaluate the effectiveness of human-computer interaction interfaces. It also highlights the challenges of implementing standards and provides examples of successful and unsuccessful adherence to guidelines.
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ICS 463, Intro to Human Computer Interaction Design: 6 (Practice). Guidelines and Metrics Chapters 24-25
Guidelines: Principles • Generic high level advice, such as: • Know the user population • Support rather than obstruct the task • Reduce cognitive load • Make state and functionality visible • Maintain consistency and clarity • Engineer for errors • Design for user growth • Requires interpretation to apply • Can help focus design
Guidelines: Design Rules • Specific instructions, such as: • Always issue a warning before deleting • Provide “undo” for all actions • The first two menus should be “File” and “Edit” • Do not display more than 7+-2 items • Represent dates with mm/dd/yy in North America and dd.mm.yy in Europe • Represent decimals with xxx.xx in North America and xxx,xx in Europe • Easy to apply but limited generality • Sometimes wrong!Which above is wrong?
Tradeoffs • Minimizing complexity and visual search versus minimizing context changes needed • e.g., how much info on your home page? http://www.math.hawaii.edu/ http://www.ics.hawaii.edu • Making all choices visible versus not obscuring workspace • e.g. how many items in a menu? (Communicator) • Ease of learning versus speed of execution • e.g., menu selection versus control keys
Standards • Standards look like guidelines and rules but say “shall” and “must” • Reasons for standards in HCI: • Quality of design • Learnability and transfer of skills • Shared terminology and models • Health and safety (digital as well as physical) • Interoperability • Corporate identity
Standards Organizations • International Standards Organization (ISO) • ISO 9241 - Work with Visual Display Terminals • International Electrotechnical Commission (IEC) • Joint Technical Committee (JTC1) *** • Institute of Electrical and Electronics Engineers (IEEE) • Learning Technology Standards Committee *** *** Coming soon to a university near you!
Issues with Standards etc. • Standards • are based on existing practice • take years to develop • but technology changes rapidly • Often, it’ll cost you! • There are also: • Government Standards • De facto standards: QUERTY, MS Office • House style guides: Windows and Macintosh style guides
Metrics • Important for objective comparisons: “if you can’t measure it you don’t know it” • Misleading if you measure the wrong thing! • Types of metrics: • Analytic: based on design notation or features of interface • Performance: user’s performance with working prototype • Subjective: user’s perceptions of software and its use
Some Metrics • Analytical • Predicted number of keystrokes needed (GOMS) • Number of command actions that are hidden versus visible • Complexity and organization of interface • Performance • Time to complete task • Number or percent of task completed per unit time • Number of errors per task or unit time • Time required to reach task criterion or error rate • Rate of use of help system • Quality of task product • Subjective (“Psychometric”) • User’s attitude towards the system • Perception of efficiency • Perception of helpfulness • Perception of control • Perception of learnability Consider also group level measurements
Assignment 5 1. Find two examples of an interface or system that • follows a guideline or design rule successfully • follows a guideline or design rule inappropriately • violates a guideline or design rule with detrimental results • violates a guideline or design rule with positive results • (Choose two of these.) • Make screen dumps and put them in a web page with a brief explanation. • Send me the URL
Project Assignment X (This will not be graded but should be done.) • Write an initial list of metrics that you think would be appropriate for your project. These metrics could be used for (indicate which): • Comparing designs • Measuring improvements as result of change • Setting absolute thresholds • Email it to me (one email per project, with cc to all project members)
Let’s look at your projects … … and mine