Integrating usability into use cases: A methodology for user interface design

The success of software user interface design involves a complementary effort to design functionality as well as usability. As a means to address the design problems that result in usability concerns being ignored in the early stages of the software development process, a conceptual framework for integrating methods from both the user-centered design approach and the use-case-driven development process was proposed in the present study. Specifically, four methods for accomplishing this framework were introduced: (1) develop integrated use cases, (2) apply psychological theories to identify interface objects, (3) discover user interface patterns, and (4) cost-justify use of usability evaluation methods. ^ A three-phase empirical study was conducted to provide empirical support for application of the proposed design methodology. In Phase 1 of the empirical study, the needs for a web-based decision-support application were identified, and the usability concerns were gathered through a survey study. In Phase 2, user interface specifications that integrated functional as well as usability requirements were developed and then implemented by software developers in a laboratory setting. In Phase 3, a usability evaluation was conducted to examine the web applications developed in Phase 2. ^ The present study has provided empirical evidence that application of the integrated design methodology as proposed can (1) lead to development of more useful and usable user interfaces, compared to system-oriented specifications, and (2) represent a design model that is more likely to be adapted by developers to form a consistent development model. Therefore, the proposed methodology has the potential to benefit user-centered design in three aspects: (1) to improve overall human factors effectiveness by integrating usability early into standardized functional specifications, (2) to facilitate construction of appropriate development models to implement a user interface that are more likely to satisfy user needs and preferences, and (3) to provide insights into developing alternative methods and tools for enabling adoption of user-centered design in the current mainstream software development process.