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?

Smith & Mosier 1986

Tradeoffs Minimizing complexity and visual search versus minimizing context changes needed –e.g., how much info on your home page? 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 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 it to me (one per project, with cc to all project members)

Let’s look at your projects … … and mine