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Working with a large information technology organization in industry, we have been investigating how a repository of organization-specific usability guidelines can be created and used to produce high quality end-user applications. Our approach is to create tools and methods in which software development organizations can develop and evolve usability guidelines based on the kinds of applications they develop. This information can then be used to match customer requirements to specific interface techniques that have proven effective for similar users and application domains. This is supported through a case-based system that attaches experience cases to guidelines to help find, explain, specialize, and extend usabiltiy guidelines.
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The recent proliferation of GUI and application builders, such as Visual Basic and Delphi, have made it extremely easy to arrange interface widgets on a screen. But developers are discovering that user interface issues are not restricted to the widget layout and look-and-feel tools provided by these environments. A significant amount of time, effort, and dollars are expended by users working with interfaces designed by developers with little or no usability training. This is particularly crucial in in-house development settings that create software for businesses that depend on information technology to run their operations. Better training and usability evaluations are certainly key aspects of improving the current state of affairs, but a complementary approach is to provide developers with context-sensitive guidance about usability issues.
Although user-centered techniques such as participatory design and usability evaluations cannot fully be replaced, interface guidelines can support developers by disseminating key usability knowledge. In general, there are two kinds of guidelines. Style guides are mostly concerned with look-and-feel issues and describing how and when widgets should be used [2, 5]. Usability guidelines provide general purpose advice on widget layout and usability principles in a platform-independent manner [6].
Each type of guideline has strengths and weaknesses. Style guides can help developers create consistent interfaces within and across applications and usability guidelines give sound advice on current usability techniques. But current guidelines lack contextual information to help developers assess whether a guideline is applicable or how a guideline can be applied to a given set of circumstances. Stating that the application should "Allow the user to control the dialogue" is sound advice, but it is unclear how this should be applied, for example, to a system for maintaining locomotive engines.
On-line versions of guidelines have been created to improve their accessibility with hypertext-based search systems [1, 4]. But formidable problems remain with respect to defining when guidelines are applicable or how guidelines can be refined to meet user task requirements for a specific set of users and a specific type of application. Work on usability issues has become voluminous to the point that it is difficult to determine which principles are applicable to a given design problem, and the continuing proliferation of technology makes it difficult to find a good fit. But little research to date has been done to accumulate knowledge about interface design in a form that can be proactively applied to the development of interactive systems.
In conjunction with Union Pacific Railroad's (UPRR) newly founded human factors group [3], we have been exploring how software development organizations can create usability guidelines that are tailored to the business needs of an organization. UPRR has recently developed an on-line corporate user interface style guide to ensure compliance with corporate and industry standards. This system helps developers achieve Windows compliance, and makes commendable use of good and bad examples to illustrate guideline principles.
Our effort has focused on combining on-line guideline systems with organizational memory techniques that collect and disseminate the accumulated experiences of developers in the organization. The approach starts with a set of guidelines and principles that have been approved by human factors experts. As interfaces are developed, developers record which guidelines were used and other criteria that significantly impacted interface design. These experiences are stored in "cases" that are attached to the general guidelines. The cases demonstrate how different guidelines have been applied to interface designs, and can serve as examples of interface designs (both good and bad) that can be used by subsequent developers.
Instead of relying solely on abstract, general-purpose guidelines or widget specifications, organization-specific guidelines capture and evolve information about specific user populations, tasks, applications, and interface techniques based on the kinds of applications developed by the organization. This information is used to match customer requirements to specific interface techniques that have proven effective for similar users, tasks, and application domains. Effective use of usability guidelines of this kind will result in the design and development of systems that are well-suited to end-user tasks.
Guidelines and cases can provide helpful nuggets of information, but suffer from their disconnected nature. For a given interface design problem, it is difficult to know which guidelines should be followed, how different guidelines interact and/or contradict each other, and when the guidelines should be followed. We are currently creating tools and methods to help developers organize guidelines into domain-specific knowledge that is created and applied as the organization gains experience with usability issues. This knowledge serves to capture principles and guidelines that are emerging in development efforts throughout the organization, thus providing timely information on areas in need of standard practices and procedures.
We are investigating how dynamic checklists can be employed to disseminate knowledge about user interface design. Checklists provide information about the steps that are needed to achieve a certain development task. Each checklist item is accompanied by a description of the tasks to be performed before checking off the item as well as a help system that can explain or automatically perform the task (a kind of "wizard"). Checklists are created by development teams as documentation of their efforts and progress and placed in a repository for future use.
Developers wishing to find applicable checklists engage in a question/answer session that guides developers toward an appropriate set of guidelines. Each question/answer pairing is associated with a checklist. After each question is answered, the system computes a score for the applicable checklists and displays them for further perusal. The developers can utilize and/or change the checklist to suit their specific needs.
To be an effective support tool for developing interfaces, the guidelines and cases in the repository must be able to evolve with the organization's changing needs. As the previous section illustrates, we are carefully designing development processes that provide immediate benefit in addition to recording decisions for future efforts. We are seeking to fit our approach into the organizational infrastructure in a natural manner, yet transforming development activities into a knowledge collection process that improves the repository of guidelines and cases.
Procedures for achieving conformance to established corporate guidelines can be used to capture emerging usability issues. During design reviews, developers and human factors personnel agree on guidelines that should be used to develop the application. If conformance is achieved, developers create a case and attaches it to the applicable guidelines. If conformance is not achieved, developers provide rationale for why a guideline was violated or not followed. The rationale is used as a precedent for an exception to the guideline or suggestions for improvements to the guideline. Because this information is certified by human factors or other qualified individuals, the veracity of exceptions is assured and can become part of the organization standard. This kind of procedure is similar to that used in the Designer Assistant and is an important element of creating a "living design memory" [7] that evolves with the organization's needs.
As the cases accumulate, the knowledge contained in the repository becomes increasingly tailored to the kinds of design problems that frequently occur in the organization. The repository therefore serves not only as a means to disseminate usability knowledge, but also helps an organization learn what does and does not work in their development context. The method also naturally incorporates an evolutionary, continuous, process of improvement that evolves with ever-changing development technology and business context.
Interface design cannot be reduced to following a cookbook, but there is a need to re-use knowledge and build on the successes and failures of previous and ongoing development efforts. Our approach seeks to disseminate this knowledge by building on and evolving guidelines and standards that are derived in the context of design. Cases provide examples of the guidelines and precedents that establish the boundaries of guideline applicability. Creating contextualized guidelines in this manner provides interface designers with information that can reduce the number of iterations and shorten design cycles while producing interfaces that effectively meet end-user needs.
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