Four Basic Activities to Reach Optimal Usability
by Dr. Bob Bailey
What would be the best research-based approach for designing usable and useful computer-based systems? Although there are many unanswered questions, the research over the past few years provides some clear suggestions about creating high-quality user interfaces.
There is at least one good study (G. Bailey, 1993) indicating that user-oriented designers are superior to computer-oriented designers when making user interface decisions. In that research, the user-oriented designers were able to develop a user interface that elicited reliably better user performance than did the computer-oriented designers. In fact, the programmer’s last iteration elicited a human performance level that was about the same as the user-oriented designer’s first iteration.
Guideline: Ensure that user-oriented designers are responsible for making the majority of important user interface decisions. This includes all user-oriented decisions, beginning when the system’s tasks (functions) are still being defined.
One of the secrets of designing effective, efficient and satisfying user interfaces is to evaluate and choose from among many, many options (McGrew, 2001; Ovaska and Raiha, 1995). This means that several alternative ways of having people interact with a new system should be put on the table for consideration. In general, the more alternatives that are considered before deciding on the best one, the better will be the initial interface. Once the initial interface has been defined, designers can use an iterative approach to make improvements.
Keep in mind that it is far better to start the iterative process at a high level (with a better interface), rather than trying to do enough iterations to make up for poor design decisions in the beginning. In fact, it is possible that designers will not have the time, resources or patience to perform enough iterations to ever make up for problems encountered by starting with a set of poor interface decisions.
Guideline: Never select the final set of initial design ideas, such as the homepage layout, the overall navigation scheme, or the final Web site content, until a large number of alternatives are first considered.
The Research-Based Guidelines (Koyani, Bailey, Nall, 2004) reflect the current knowledge and understanding of major user interface issues. Use the guidelines (or your own research-based guidelines) to make important user interface decisions as part of an early in the Web planning process, rather than as part of a “back-end” test and evaluation program. Every person on the design team should be aware of the major topics dealt with by the guidelines before making any interface decisions. This helps to ensure that the best possible decisions are made, and also helps to have consistency across all interface decisions.
Guideline: Ensure that all members of the design team have access to research-based guidance at the beginning of the design process, and that they are used as a design standard to help ensure consistency among design decisions.
The best way to ensure a good user interface is to create a prototype and immediately begin conducting usability tests (cf. Tan, Liu, Bishu, Muralidhar, and Meyer, 2001). Initially, prototypes may be low-fidelity paper prototypes, and the tests may be relatively low-level usability evaluations. As the prototype becomes more mature, the usability testing will be much more sophisticated. Eventually, a highly quantified baseline test can be conducted to help in determining when usability objectives are met.
Guideline: Begin testing and making changes as soon as possible. The iterative process can continue long after the Web site has been posted.
If there is not enough time or resources to be more systematic in ensuring a good interface with a Web-based product, then at least do the four activities mentioned above. Performing these activities will help ensure that:
- The designers are user-oriented
- Many alternatives are considered
- Most of the important decisions are research-based
- The product is continually improved using usability testing and an iterative design philosophy
Bailey, G.D., (1993), Iterative methodology and designer training in human computer interface design, Proceedings of InterCHI'93, 198.
Koyani, S., Bailey, R.W. and Nall, J. (2004), Research-Based Web Design and Usability Guidelines, http://usability.gov/pdfs/guidelines.html.
McGrew, J. (2001), Shortening the human computer interface design cycle: A parallel design process based on the genetic algorithm, Proceedings of the Human Factors and Ergonomics Society 45th Annual Meeting, 603-606.
Ovaska, S. and Raiha, K.J. (1995), Parallel design in the classroom, Proceedings of CHI'95, 264-265.
Tan, W., Liu, D., Bishu, R. R., Muralidhar, A. and Meyer, J. (2001), Design improvements through user testing, Proceedings of the Human Factors and Ergonomics Society 45th Annual Meeting, 1181-1185.