Designing for Mobile Devices

Designing user interfaces for mobile devices poses unique challenges relative to design for traditional desktop applications. The most significant of these is reduced screen size. Designing a successful PDA application isn't about densely packing buttons or data into a small display or spreading that functionality across endless sub-screens. As Rob Haitani, Interface Designer of the original Palm OS stated, "If you're trying to make a simple design on a small screen, you're not providing value to the user when you give them a whole slew of buttons. You're being lazy or indecisive, and the result of your inability to make tradeoffs is a poor user experience."

The Engagement

CaseMed Decision Support develops drug therapy guidance software that uses a proprietary case-based reasoning engine. Early in their product concept stage, CaseMed asked Human Factors MD to design and develop a proof of concept prototype for a PDA-based application.

Results

CaseMed's reasoning engine presents users with questions about a patient's symptoms and history, along with candidate therapy solutions ranked by goodness-of-fit. A key feature of the reasoning engine is that it enables physicians to answer questions in any order. Whenever a question is answered, the engine incorporates the response, finds its best-case matches, and updates the question and candidate therapy lists and rankings. Research showed that users of a related desktop application got more value from the tool, if multiple questions and candidate solutions were displayed simultaneously. To maximize the number of questions and solutions visible at one time on a small display, we created a summary "reasoning" screen with abbreviated questions and candidate solutions. The abbreviated questions provided enough detail for physicians to answer most questions directly, without have to access the full text of the question (a tap away).

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