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What is Usability?

“Usability” is often used to describe two related, but distinct, concepts. Usability can define the quality of a system, or it can refer to a process or set of techniques implemented during a design and development project. This second aspect is sometimes described as usability engineering, and is more accurately called user-centered design.

As usability refers to the quality of a system and the process of designing a usable system is “the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use (from the ISO 9241-11).”

Broken down and simplified, ISO 9241-11 outlines that:

1. There are specified users of the system.
2. Those users have a set of specific goals.
3. The system should allow user goals to be met effectively, efficiently and with an outcome that at least meet the goals of the user.
4. The system will be used in a particular context (within a physical location or business process).

A system that is designed to consider all of these aspects is one that is user-centered.

Why is Usability Important?

When a system is highly functional for users, it is extremely beneficial to business.

As users achieve their tasks more easily and efficiently, not only is a feeling of achievement that people get when they use a computer system without frustration fostered that should not be underestimated, but time is saved and productivity is increased. On the other hand, when systems are difficult to use, an individual user cost may be small. Yet taken incrementally in terms of lost sales, customer satisfaction, staff productivity, manufacturing downtime and support requirements, the cumulative price tag may be cripplingly vast. When people are confronted with a difficult-to-use system, they tend to avoid it as much as possible, if not altogether.

How is Usability Attained?

The only way to determine whether a system is usable is to get end users to use it for real tasks.

The main way this is done is through usability testing. In a usability test, users of the system attempt tasks while being observed. The observers don’t tell the usability test participant how to use the system and they don’t answer questions - it is as if the participant were doing the tasks by themselves in real life.

The usability test identifies primary usability problems with a system (enabling them to be fixed); and collects quantitative measures of effectiveness and satisfaction before release.

The key aspects of a usability test are:

1. Participants involved are examples of existing or future users of the system (not managers or business owners).
2. Participants perform realistic tasks on the system.
3. The usability test is set up in a way that is as close to the normal context as possible, with the observers being integrated seamlessly or removed entirely from participant interaction.

What type of usability testing you do depends on the depth of usability issues you want to root out. If you are primarily concerned with major issues, a small and fast team will be able to handle it. A more professional lab setting with a greater number of usability testers will be required for more refinement. It doesn’t take a whole lot of thought to realize that the conclusions reached by some major studies make perfect sense, but it does take a great deal of effort to step out of one’s field of expertise even for great rewards.

Usability testing is not a cure-all. Fixing problems in a design is never as effective or as efficient as preventing design flaws in the first place. Of course, a perfect user-centered design is more of an ideal to aspire to than an achievable reality—but the two, each in concert, may help your business attain user harmony.

Friday, October 19th, 2007 Both comments and pings are currently closed.

By Haley January Eckels